Benchmarks

All benchmarks run on an AMD Ryzen 9 9900X 12-Core Processor (24 cores, 121 GB RAM), averaged over 100 runs after 10 warmup iterations. Times in milliseconds (lower is better) unless noted otherwise.

Startup Latency

How fast each shell can execute a command and exit.

shell -c 'true' round-trip

dash

0.24ms

0.42ms

bash

0.43ms

zsh

0.54ms

lash

0.57ms

fish

5.8ms

shell	median (ms)	startup (ms)	stddev (ms)	throughput (MB/s)
dash	0.24	0.24	0.05	—
sh	0.42	0.43	0.04	—
bash	0.43	0.43	0.04	—
zsh	0.54	0.54	0.05	—
lash	0.57	0.57	0.05	—
fish	5.75	5.77	1.26	—

shell -c 'echo x' round-trip

dash

0.22ms

bash

0.01ms

zsh

0.52ms

lash

0.03ms

fish

0.06ms

shell	median (ms)	startup (ms)	stddev (ms)	throughput (MB/s)
dash	0.22	0.22	0.06	—
bash	0.41	0.40	0.08	—
sh	0.42	0.41	0.10	—
zsh	0.52	0.52	0.08	—
lash	0.60	0.57	0.15	—
fish	6.41	6.35	1.63	—

shell -c 'echo x | cat' round-trip

dash

0.29ms

lash

0.13ms

0.36ms

bash

0.36ms

zsh

0.34ms

fish

0.29ms

shell	median (ms)	startup (ms)	stddev (ms)	throughput (MB/s)
dash	0.50	0.21	0.03	—
lash	0.73	0.60	0.04	—
sh	0.75	0.39	0.05	—
bash	0.76	0.40	0.06	—
zsh	0.86	0.52	0.10	—
fish	6.07	5.78	0.57	—

Pipe Throughput

Raw data throughput through pipes. MB/s charts are higher-is-better.

64MB through single pipe, minimal output

lash-turbo

145125 MB/s

bash

9315 MB/s

dash

8847 MB/s

8740 MB/s

lash

8623 MB/s

zsh

8376 MB/s

fish

5264 MB/s

shell	median (ms)	startup (ms)	stddev (ms)	throughput (MB/s)
lash-turbo	0.44	0.60	0.06	145125
bash	6.87	0.47	0.30	9315
dash	7.23	0.35	0.61	8847
sh	7.32	0.53	0.55	8740
lash	7.42	0.67	0.54	8623
zsh	7.64	0.62	0.60	8376
fish	12.16	5.63	0.63	5264

64MB through 3 cat stages

lash-turbo

142222 MB/s

8277 MB/s

dash

8101 MB/s

bash

8072 MB/s

lash

7842 MB/s

zsh

7498 MB/s

fish

4566 MB/s

shell	median (ms)	startup (ms)	stddev (ms)	throughput (MB/s)
lash-turbo	0.45	0.61	0.02	142222
sh	7.73	0.48	0.62	8277
dash	7.90	0.33	0.47	8101
bash	7.93	0.50	0.53	8072
lash	8.16	0.69	0.43	7842
zsh	8.54	0.72	2.69	7498
fish	14.02	6.88	0.66	4566

16MB output streamed to sink

lash-turbo

7027 MB/s

dash

6845 MB/s

lash

6270 MB/s

bash

6091 MB/s

zsh

5835 MB/s

5689 MB/s

fish

1896 MB/s

shell	median (ms)	startup (ms)	stddev (ms)	throughput (MB/s)
lash-turbo	2.28	0.63	0.32	7027
dash	2.34	0.26	0.34	6845
lash	2.55	0.63	0.25	6270
bash	2.63	0.47	0.14	6091
zsh	2.74	0.58	0.29	5835
sh	2.81	0.49	0.30	5689
fish	8.44	6.28	0.48	1896

echo|cat round-trip latency — turbo 1.1x vs forked

dash

0.24ms

lash-turbo

0.08ms

bash

0.30ms

lash

0.11ms

zsh

0.33ms

fish

0.23ms

shell	median (ms)	startup (ms)	stddev (ms)	throughput (MB/s)
dash	0.45	0.21	0.06	—
lash-turbo	0.63	0.55	0.14	—
bash	0.69	0.39	0.07	—
sh	0.69	0.39	0.08	—
lash	0.71	0.60	0.10	—
zsh	0.84	0.51	0.07	—
fish	5.94	5.71	0.41	—

1GB through single pipe, minimal output

lash-turbo

2255507 MB/s

dash

8423 MB/s

lash

8064 MB/s

fish

7875 MB/s

6602 MB/s

bash

6511 MB/s

zsh

6112 MB/s

shell	median (ms)	startup (ms)	stddev (ms)	throughput (MB/s)
lash-turbo	0.45	0.61	0.04	2255507
dash	121.57	0.52	9.62	8423
lash	126.99	1.17	6.18	8064
fish	130.03	8.01	11.16	7875
sh	155.11	0.96	10.01	6602
bash	157.26	1.12	9.26	6511
zsh	167.53	1.38	6.34	6112

seq 1M | sort | tail — turbo 7.6x vs forked

lash-turbo

37ms

zsh

288ms

lash

289ms

dash

292ms

bash

302ms

fish

308ms

shell	median (ms)	startup (ms)	stddev (ms)	throughput (MB/s)
lash-turbo	38.10	1.29	1.64	—
zsh	288.38	0.82	5.70	—
sh	289.07	0.71	7.00	—
lash	290.07	0.99	6.53	—
dash	292.85	0.46	2.98	—
bash	302.89	1.05	9.46	—
fish	318.90	10.70	3.90	—

echo through 5 cat stages — turbo 1.0x vs forked

dash

0.52ms

lash

0.35ms

lash-turbo

0.37ms

0.62ms

bash

0.64ms

zsh

0.80ms

fish

1.2ms

shell	median (ms)	startup (ms)	stddev (ms)	throughput (MB/s)
dash	0.85	0.33	0.14	—
lash	1.02	0.67	0.46	—
lash-turbo	1.04	0.67	0.29	—
sh	1.12	0.50	0.16	—
bash	1.14	0.50	0.21	—
zsh	1.34	0.54	0.26	—
fish	9.33	8.18	2.21	—

echo through 10 cat stages — turbo 1.0x vs forked

dash

0.58ms

lash-turbo

0.49ms

lash

0.50ms

bash

0.68ms

0.71ms

zsh

1.2ms

fish

1.2ms

shell	median (ms)	startup (ms)	stddev (ms)	throughput (MB/s)
dash	0.82	0.24	0.14	—
lash-turbo	1.10	0.61	0.09	—
lash	1.12	0.62	0.08	—
bash	1.14	0.46	0.09	—
sh	1.15	0.44	0.11	—
zsh	1.78	0.55	0.16	—
fish	7.19	5.95	0.58	—

sort 100K lines — turbo 52.7x vs forked

lash-turbo

0.49ms

dash

25ms

bash

25ms

lash

25ms

zsh

25ms

fish

26ms

shell	median (ms)	startup (ms)	stddev (ms)	throughput (MB/s)
lash-turbo	0.49	0.67	0.01	—
dash	25.52	0.39	0.33	—
sh	25.63	0.57	0.28	—
bash	25.80	0.55	0.24	—
lash	25.83	0.79	0.16	—
zsh	26.03	0.69	0.48	—
fish	31.82	6.26	0.55	—

sort | head from 100K lines — turbo 9.5x vs forked

lash-turbo

1.9ms

dash

23ms

bash

23ms

lash

23ms

zsh

23ms

fish

23ms

shell	median (ms)	startup (ms)	stddev (ms)	throughput (MB/s)
lash-turbo	2.48	0.63	0.09	—
dash	23.04	0.37	0.26	—
sh	23.37	0.55	0.12	—
bash	23.45	0.59	0.25	—
lash	23.61	0.79	0.16	—
zsh	23.95	0.72	0.32	—
fish	29.79	6.33	0.72	—

sort | tail from 100K lines — turbo 6.2x vs forked

lash-turbo

3.5ms

dash

25ms

lash

25ms

bash

25ms

zsh

25ms

26ms

fish

25ms

shell	median (ms)	startup (ms)	stddev (ms)	throughput (MB/s)
lash-turbo	4.11	0.61	0.05	—
dash	25.43	0.37	0.19	—
lash	25.65	0.74	0.63	—
bash	25.87	0.56	0.12	—
zsh	25.93	0.79	0.19	—
sh	26.76	0.65	0.47	—
fish	31.14	5.88	0.59	—

grep | sort | head from 100K — turbo 5.8x vs forked

lash-turbo

1.1ms

lash

9.4ms

dash

9.8ms

bash

9.7ms

zsh

9.9ms

fish

9.7ms

shell	median (ms)	startup (ms)	stddev (ms)	throughput (MB/s)
lash-turbo	1.73	0.61	0.02	—
lash	10.02	0.63	0.14	—
dash	10.13	0.37	0.13	—
sh	10.25	0.49	0.21	—
bash	10.26	0.53	0.09	—
zsh	10.54	0.65	0.17	—
fish	16.29	6.58	0.16	—

16MB through 1 cat stage

lash-turbo

37736 MB/s

dash

6376 MB/s

bash

5742 MB/s

zsh

5456 MB/s

lash

5451 MB/s

5304 MB/s

fish

1877 MB/s

shell	median (ms)	startup (ms)	stddev (ms)	throughput (MB/s)
lash-turbo	0.42	0.57	0.03	37736
dash	2.51	0.27	0.26	6376
bash	2.79	0.52	0.35	5742
zsh	2.93	0.63	0.38	5456
lash	2.94	0.71	0.26	5451
sh	3.02	0.53	0.39	5304
fish	8.53	6.00	0.83	1877

16MB through 2 cat stages

lash-turbo

32922 MB/s

dash

5652 MB/s

zsh

4940 MB/s

bash

4853 MB/s

lash

4811 MB/s

4654 MB/s

fish

1864 MB/s

shell	median (ms)	startup (ms)	stddev (ms)	throughput (MB/s)
lash-turbo	0.49	0.64	0.01	32922
dash	2.83	0.36	0.14	5652
zsh	3.24	0.66	0.27	4940
bash	3.30	0.56	0.28	4853
lash	3.33	0.70	0.39	4811
sh	3.44	0.55	0.40	4654
fish	8.58	6.51	0.54	1864

16MB through 4 cat stages

lash-turbo

36364 MB/s

dash

5269 MB/s

lash

5189 MB/s

4812 MB/s

bash

4698 MB/s

zsh

4623 MB/s

fish

1724 MB/s

shell	median (ms)	startup (ms)	stddev (ms)	throughput (MB/s)
lash-turbo	0.44	0.62	0.08	36364
dash	3.04	0.35	0.43	5269
lash	3.08	0.65	0.20	5189
sh	3.33	0.52	0.22	4812
bash	3.41	0.56	0.17	4698
zsh	3.46	0.64	0.22	4623
fish	9.28	6.10	0.91	1724

16MB through 8 cat stages

lash-turbo

36199 MB/s

dash

4713 MB/s

4269 MB/s

bash

4263 MB/s

lash

4200 MB/s

zsh

3788 MB/s

fish

1576 MB/s

shell	median (ms)	startup (ms)	stddev (ms)	throughput (MB/s)
lash-turbo	0.44	0.58	0.03	36199
dash	3.40	0.35	0.21	4713
sh	3.75	0.52	0.41	4269
bash	3.75	0.54	0.15	4263
lash	3.81	0.72	0.32	4200
zsh	4.22	0.66	0.24	3788
fish	10.15	6.92	0.63	1576

16MB through 16 cat stages

lash-turbo

32258 MB/s

dash

2711 MB/s

bash

2649 MB/s

lash

2583 MB/s

2531 MB/s

zsh

2164 MB/s

fish

1328 MB/s

shell	median (ms)	startup (ms)	stddev (ms)	throughput (MB/s)
lash-turbo	0.50	0.64	0.03	32258
dash	5.90	0.36	0.45	2711
bash	6.04	0.61	0.37	2649
lash	6.19	0.76	0.24	2583
sh	6.32	0.55	0.71	2531
zsh	7.39	0.72	0.80	2164
fish	12.05	6.67	0.74	1328

16MB direct write to file

dash

7468 MB/s

zsh

6261 MB/s

5991 MB/s

lash-turbo

5619 MB/s

bash

5560 MB/s

lash

5435 MB/s

fish

1774 MB/s

shell	median (ms)	startup (ms)	stddev (ms)	throughput (MB/s)
dash	2.14	0.25	0.41	7468
zsh	2.56	0.56	0.10	6261
sh	2.67	0.47	0.31	5991
lash-turbo	2.85	0.64	0.34	5619
bash	2.88	0.45	0.35	5560
lash	2.94	0.61	0.38	5435
fish	9.02	6.06	0.76	1774

16MB through pipe then to file

lash-turbo

4648 MB/s

dash

4599 MB/s

zsh

4005 MB/s

bash

3939 MB/s

lash

3787 MB/s

3784 MB/s

fish

1733 MB/s

shell	median (ms)	startup (ms)	stddev (ms)	throughput (MB/s)
lash-turbo	3.44	0.72	0.27	4648
dash	3.48	0.36	0.29	4599
zsh	4.00	0.66	0.23	4005
bash	4.06	0.57	0.24	3939
lash	4.22	0.75	0.34	3787
sh	4.23	0.54	0.31	3784
fish	9.23	6.10	0.66	1733

16MB read from file through pipe

lash-turbo

4513 MB/s

lash

2808 MB/s

dash

2748 MB/s

bash

2654 MB/s

2568 MB/s

zsh

2479 MB/s

fish

1141 MB/s

shell	median (ms)	startup (ms)	stddev (ms)	throughput (MB/s)
lash-turbo	3.54	0.65	0.55	4513
lash	5.70	0.73	0.63	2808
dash	5.82	0.32	0.48	2748
bash	6.03	0.55	0.37	2654
sh	6.23	0.51	0.35	2568
zsh	6.46	0.70	0.56	2479
fish	14.02	6.84	1.29	1141

16MB to /dev/null (overhead baseline)

dash

28319 MB/s

bash

19196 MB/s

lash

19025 MB/s

18486 MB/s

zsh

18401 MB/s

lash-turbo

18223 MB/s

fish

2356 MB/s

shell	median (ms)	startup (ms)	stddev (ms)	throughput (MB/s)
dash	0.56	0.26	0.49	28319
bash	0.83	0.44	0.02	19196
lash	0.84	0.61	0.02	19025
sh	0.87	0.45	0.05	18486
zsh	0.87	0.56	0.04	18401
lash-turbo	0.88	0.63	0.28	18223
fish	6.79	6.26	1.28	2356

Scripting Operations

Common data-processing patterns across shells.

Sort 1000 lines (reverse numeric) — turbo 2.0x vs forked

lash-turbo

0.44ms

dash

0.45ms

lash

0.27ms

bash

0.50ms

0.52ms

zsh

0.56ms

fish

0.67ms

shell	median (ms)	startup (ms)	stddev (ms)	throughput (MB/s)
lash-turbo	0.44	0.63	0.02	—
dash	0.71	0.26	0.04	—
lash	0.90	0.63	0.12	—
bash	0.94	0.44	0.52	—
sh	0.97	0.45	0.46	—
zsh	1.13	0.57	0.12	—
fish	6.66	5.99	1.58	—

Sort 10000 lines (reverse numeric) — turbo 5.5x vs forked

lash-turbo

0.52ms

dash

2.5ms

lash

2.2ms

bash

2.5ms

zsh

2.5ms

fish

4.4ms

shell	median (ms)	startup (ms)	stddev (ms)	throughput (MB/s)
lash-turbo	0.52	0.69	0.03	—
dash	2.83	0.28	0.22	—
lash	2.85	0.62	0.33	—
bash	2.97	0.44	0.43	—
sh	3.00	0.46	0.42	—
zsh	3.07	0.55	0.08	—
fish	11.19	6.74	1.73	—

Filter odd-ending numbers from 1K via grep — turbo 1.0x vs forked

lash-turbo

0.20ms

lash

0.21ms

bash

0.41ms

0.44ms

dash

0.55ms

zsh

0.52ms

fish

0.54ms

shell	median (ms)	startup (ms)	stddev (ms)	throughput (MB/s)
lash-turbo	0.79	0.59	0.03	—
lash	0.82	0.61	0.04	—
bash	0.85	0.44	0.03	—
sh	0.87	0.43	0.13	—
dash	0.88	0.33	0.13	—
zsh	1.09	0.57	0.24	—
fish	7.42	6.88	1.00	—

Filter even numbers from 10K via awk — turbo 1.0x vs forked

dash

1.6ms

lash

1.4ms

1.5ms

bash

1.6ms

lash-turbo

1.4ms

zsh

1.7ms

fish

2.0ms

shell	median (ms)	startup (ms)	stddev (ms)	throughput (MB/s)
dash	1.85	0.26	0.24	—
lash	1.98	0.63	0.10	—
sh	1.99	0.45	0.31	—
bash	2.00	0.44	0.07	—
lash-turbo	2.00	0.63	0.09	—
zsh	2.24	0.56	0.39	—
fish	9.46	7.51	1.10	—

Transform (x2) 1K lines via awk — turbo 1.0x vs forked

dash

0.70ms

lash

0.54ms

lash-turbo

0.53ms

0.74ms

bash

0.74ms

zsh

0.75ms

fish

1.7ms

shell	median (ms)	startup (ms)	stddev (ms)	throughput (MB/s)
dash	0.96	0.26	0.04	—
lash	1.15	0.61	0.16	—
lash-turbo	1.15	0.62	0.04	—
sh	1.17	0.43	0.10	—
bash	1.19	0.45	0.12	—
zsh	1.33	0.58	0.47	—
fish	9.00	7.30	2.84	—

Transform (x2) 10K lines via awk — turbo 1.0x vs forked

dash

1.8ms

lash

1.6ms

lash-turbo

1.6ms

1.9ms

bash

2.0ms

zsh

2.0ms

fish

2.6ms

shell	median (ms)	startup (ms)	stddev (ms)	throughput (MB/s)
dash	2.10	0.28	0.78	—
lash	2.21	0.62	0.13	—
lash-turbo	2.23	0.63	0.08	—
sh	2.36	0.45	0.38	—
bash	2.45	0.45	0.79	—
zsh	2.68	0.70	0.40	—
fish	9.13	6.53	1.86	—

Sort 1K then take first 10 (sort | head) — turbo 1.1x vs forked

dash

0.47ms

lash-turbo

0.03ms

lash

0.27ms

bash

0.50ms

0.53ms

zsh

0.53ms

fish

0.67ms

shell	median (ms)	startup (ms)	stddev (ms)	throughput (MB/s)
dash	0.74	0.27	0.22	—
lash-turbo	0.81	0.78	0.38	—
lash	0.88	0.61	0.04	—
bash	0.93	0.43	0.03	—
sh	0.97	0.44	0.25	—
zsh	1.09	0.56	0.04	—
fish	8.31	7.64	1.67	—

Filter even then double from 1K (awk combo) — turbo 1.1x vs forked

dash

0.74ms

lash-turbo

0.54ms

lash

0.56ms

bash

0.79ms

0.87ms

zsh

0.85ms

fish

0.84ms

shell	median (ms)	startup (ms)	stddev (ms)	throughput (MB/s)
dash	1.00	0.26	0.03	—
lash-turbo	1.16	0.62	0.26	—
lash	1.23	0.67	0.13	—
bash	1.26	0.47	0.03	—
sh	1.33	0.46	0.13	—
zsh	1.41	0.56	0.11	—
fish	7.38	6.54	2.25	—

Filter+sort+take pipeline from 1K — turbo 1.1x vs forked

dash

0.80ms

lash-turbo

0.48ms

lash

0.59ms

bash

0.82ms

0.84ms

zsh

0.91ms

fish

1.3ms

shell	median (ms)	startup (ms)	stddev (ms)	throughput (MB/s)
dash	1.06	0.26	0.12	—
lash-turbo	1.08	0.60	0.04	—
lash	1.22	0.63	0.33	—
bash	1.28	0.46	0.14	—
sh	1.28	0.44	0.09	—
zsh	1.49	0.58	0.35	—
fish	7.36	6.06	2.12	—

Substring grep '42' in 10K lines — turbo 1.0x vs forked

dash

0.41ms

lash

0.20ms

lash-turbo

0.26ms

bash

0.44ms

0.45ms

zsh

0.47ms

fish

1.6ms

shell	median (ms)	startup (ms)	stddev (ms)	throughput (MB/s)
dash	0.68	0.27	0.02	—
lash	0.82	0.62	0.15	—
lash-turbo	0.86	0.60	0.05	—
bash	0.89	0.45	0.35	—
sh	0.90	0.45	0.04	—
zsh	1.04	0.57	0.16	—
fish	7.73	6.14	1.83	—

Sort 1M lines (reverse numeric) — turbo 14.9x vs forked

lash-turbo

19ms

bash

299ms

lash

299ms

dash

299ms

300ms

zsh

304ms

fish

311ms

shell	median (ms)	startup (ms)	stddev (ms)	throughput (MB/s)
lash-turbo	20.15	0.93	0.49	—
bash	299.44	0.72	3.82	—
lash	299.79	1.07	2.52	—
dash	299.98	0.64	2.66	—
sh	300.51	0.79	5.20	—
zsh	305.48	1.01	5.29	—
fish	321.15	10.48	2.79	—

Filter lines starting with even digit from 1M — turbo 20.0x vs forked

lash-turbo

0.58ms

dash

11ms

bash

11ms

lash

11ms

zsh

12ms

fish

12ms

shell	median (ms)	startup (ms)	stddev (ms)	throughput (MB/s)
lash-turbo	0.58	0.79	0.03	—
dash	11.20	0.35	0.26	—
bash	11.48	0.49	0.20	—
lash	11.59	0.75	0.82	—
sh	11.61	0.58	1.26	—
zsh	12.16	0.66	1.50	—
fish	20.48	8.89	2.46	—

Prepend prefix to 1M lines via sed — turbo 75.6x vs forked

lash-turbo

0.47ms

dash

35ms

bash

34ms

zsh

34ms

lash

35ms

38ms

fish

35ms

shell	median (ms)	startup (ms)	stddev (ms)	throughput (MB/s)
lash-turbo	0.47	0.61	0.04	—
dash	35.28	0.55	0.76	—
bash	35.40	1.05	1.12	—
zsh	35.50	1.03	1.66	—
lash	35.52	0.93	0.73	—
sh	38.32	0.68	1.31	—
fish	44.06	9.11	2.36	—

Sort+head+sort+tail pipeline from 100K — turbo 5.8x vs forked

lash-turbo

6.3ms

dash

38ms

39ms

zsh

39ms

lash

39ms

fish

38ms

bash

44ms

shell	median (ms)	startup (ms)	stddev (ms)	throughput (MB/s)
lash-turbo	7.02	0.69	0.20	—
dash	38.79	0.41	0.34	—
sh	39.58	0.66	1.14	—
zsh	39.61	0.75	0.53	—
lash	40.71	1.23	0.78	—
fish	44.53	6.14	1.05	—
bash	45.04	0.86	7.15	—

5-stage pipeline: grep+sort+head+sort+wc on 500K — turbo 4.3x vs forked

lash-turbo

23ms

lash

101ms

bash

102ms

zsh

102ms

dash

103ms

fish

103ms

shell	median (ms)	startup (ms)	stddev (ms)	throughput (MB/s)
lash-turbo	23.57	0.94	2.15	—
lash	101.64	0.99	2.73	—
bash	102.22	0.61	0.58	—
sh	102.27	0.64	0.42	—
zsh	102.79	0.76	1.09	—
dash	103.83	0.42	1.07	—
fish	110.06	6.97	0.76	—

Generate+sort+uniq+sort pipeline from 100K — turbo 8.8x vs forked

lash-turbo

22ms

lash

197ms

bash

200ms

201ms

dash

200ms

zsh

204ms

fish

203ms

shell	median (ms)	startup (ms)	stddev (ms)	throughput (MB/s)
lash-turbo	22.54	0.85	0.81	—
lash	197.89	1.12	0.93	—
bash	200.91	0.74	4.42	—
sh	201.50	0.94	6.46	—
dash	202.53	2.10	3.46	—
zsh	205.52	1.26	3.10	—
fish	211.39	8.78	5.29	—

100k small lines through pipe — turbo 2.6x vs forked

lash-turbo

0.42ms

dash

0.66ms

lash

0.50ms

bash

0.68ms

0.69ms

zsh

0.73ms

fish

1.1ms

shell	median (ms)	startup (ms)	stddev (ms)	throughput (MB/s)
lash-turbo	0.42	0.59	0.02	—
dash	0.90	0.24	0.07	—
lash	1.09	0.59	0.05	—
bash	1.11	0.43	0.03	—
sh	1.12	0.43	0.03	—
zsh	1.28	0.55	0.03	—
fish	6.70	5.62	0.53	—

1M small lines through pipe — turbo 10.0x vs forked

lash-turbo

0.43ms

dash

3.9ms

lash

3.7ms

3.9ms

bash

4.0ms

zsh

4.0ms

fish

4.4ms

shell	median (ms)	startup (ms)	stddev (ms)	throughput (MB/s)
lash-turbo	0.43	0.59	0.04	—
dash	4.14	0.26	0.09	—
lash	4.29	0.61	0.10	—
sh	4.35	0.44	0.06	—
bash	4.41	0.44	4.56	—
zsh	4.50	0.55	0.18	—
fish	10.48	6.04	0.79	—

100k lines through grep filter — turbo 4.1x vs forked

lash-turbo

0.48ms

dash

1.6ms

lash

1.3ms

1.6ms

bash

1.6ms

zsh

1.7ms

fish

2.3ms

shell	median (ms)	startup (ms)	stddev (ms)	throughput (MB/s)
lash-turbo	0.48	0.64	0.01	—
dash	1.84	0.27	0.08	—
lash	1.95	0.61	0.48	—
sh	2.03	0.45	0.09	—
bash	2.10	0.46	0.06	—
zsh	2.25	0.59	0.07	—
fish	8.00	5.70	0.54	—

single fork+exec (no pipe) — turbo 1.0x vs forked

dash

0.30ms

bash

0.44ms

zsh

0.59ms

lash-turbo

0.61ms

lash

0.01ms

fish

0.01ms

shell	median (ms)	startup (ms)	stddev (ms)	throughput (MB/s)
dash	0.30	0.30	0.06	—
bash	0.44	0.47	0.04	—
sh	0.44	0.46	0.04	—
zsh	0.59	0.60	0.05	—
lash-turbo	0.61	0.61	0.04	—
lash	0.63	0.62	0.06	—
fish	5.69	5.68	0.46	—

2-stage no-op pipe setup — turbo 1.1x vs forked

dash

0.09ms

lash-turbo

0.04ms

bash

0.13ms

lash

0.04ms

zsh

0.09ms

fish

0.05ms

shell	median (ms)	startup (ms)	stddev (ms)	throughput (MB/s)
dash	0.40	0.31	0.04	—
lash-turbo	0.60	0.56	0.05	—
bash	0.62	0.49	0.04	—
sh	0.62	0.49	0.04	—
lash	0.66	0.62	0.05	—
zsh	0.69	0.60	0.07	—
fish	5.82	5.77	0.58	—

5-stage no-op pipe setup — turbo 0.9x vs forked

dash

0.16ms

bash

0.28ms

0.27ms

lash

0.17ms

zsh

0.26ms

lash-turbo

0.19ms

fish

0.01ms

shell	median (ms)	startup (ms)	stddev (ms)	throughput (MB/s)
dash	0.40	0.24	0.20	—
bash	0.77	0.49	0.05	—
sh	0.77	0.50	0.06	—
lash	0.78	0.61	0.04	—
zsh	0.81	0.55	0.14	—
lash-turbo	0.84	0.65	0.05	—
fish	5.83	5.82	0.77	—

10-stage no-op pipe setup — turbo 1.0x vs forked

dash

0.27ms

0.37ms

bash

0.39ms

lash

0.40ms

lash-turbo

0.36ms

zsh

0.50ms

fish

0.05ms

shell	median (ms)	startup (ms)	stddev (ms)	throughput (MB/s)
dash	0.51	0.24	0.04	—
sh	0.79	0.42	0.12	—
bash	0.82	0.43	0.18	—
lash	0.99	0.59	0.05	—
lash-turbo	1.00	0.64	0.05	—
zsh	1.03	0.53	0.12	—
fish	5.77	5.72	0.56	—

Turbo Mode (lash vs lash-turbo)

Turbo mode rewrites common pipelines into native array operations — no fork/exec overhead.

sort 1K lines — turbo 2.0x vs forked

lash-turbo

0.47ms

lash

0.31ms

shell	median (ms)	startup (ms)	stddev (ms)	throughput (MB/s)
lash-turbo	0.47	0.62	0.05	—
lash	0.94	0.63	0.03	—

sort -n 1K lines — turbo 2.3x vs forked

lash-turbo

0.40ms

lash

0.31ms

shell	median (ms)	startup (ms)	stddev (ms)	throughput (MB/s)
lash-turbo	0.40	0.54	0.05	—
lash	0.94	0.63	0.02	—

sort -rn 1K lines — turbo 1.9x vs forked

lash-turbo

0.49ms

lash

0.32ms

shell	median (ms)	startup (ms)	stddev (ms)	throughput (MB/s)
lash-turbo	0.49	0.66	0.03	—
lash	0.95	0.63	0.06	—

grep pattern from 1K lines — turbo 1.1x vs forked

lash-turbo

0.21ms

lash

0.24ms

grep -v pattern from 1K lines — turbo 1.0x vs forked

lash-turbo

0.26ms

lash

0.29ms

head -10 from 1K lines — turbo 2.1x vs forked

lash-turbo

0.39ms

lash

0.16ms

tail -10 from 1K lines — turbo 1.7x vs forked

lash-turbo

0.47ms

lash

0.16ms

uniq 1K sorted lines — turbo 1.1x vs forked

lash-turbo

0.35ms

lash

0.33ms

tac (reverse) 1K lines — turbo 1.8x vs forked

lash-turbo

0.47ms

lash

0.19ms

wc -l count 1K lines — turbo 1.8x vs forked

lash-turbo

0.46ms

lash

0.22ms

sort | head -10 from 1K — turbo 1.6x vs forked

lash-turbo

0.07ms

lash

0.37ms

grep | sort | tail from 1K — turbo 1.0x vs forked

lash-turbo

0.23ms

lash

0.32ms

sort | uniq from 1K — turbo 1.4x vs forked

lash-turbo

0.08ms

lash

0.27ms

sort | head -10 from 10K — turbo 2.6x vs forked

lash-turbo

0.30ms

lash

1.6ms

sort | tail -10 from 10K — turbo 2.8x vs forked

lash-turbo

0.30ms

lash

1.8ms

sort -n | head -10 from 10K — turbo 3.4x vs forked

lash-turbo

0.19ms

lash

1.9ms

sort -n | tail -10 from 10K — turbo 3.0x vs forked

lash-turbo

0.36ms

lash

2.1ms

sort -r | head -10 from 10K — turbo 2.8x vs forked

lash-turbo

0.31ms

lash

1.8ms

sort -r | tail -10 from 10K — turbo 3.1x vs forked

lash-turbo

0.29ms

lash

2.0ms

sort -rn | head -10 from 10K — turbo 3.1x vs forked

lash-turbo

0.36ms

lash

2.1ms

sort -rn | tail -10 from 10K — turbo 3.2x vs forked

lash-turbo

0.27ms

lash

2.4ms

sort | head -10 from 100K — turbo 5.7x vs forked

lash-turbo

2.9ms

lash

19ms

sort -n | head -10 from 100K — turbo 9.7x vs forked

lash-turbo

1.8ms

lash

23ms

sort -rn | head -10 from 100K — turbo 6.0x vs forked

lash-turbo

3.5ms

lash

24ms

sort | tail -10 from 100K — turbo 6.6x vs forked

lash-turbo

2.8ms

lash

22ms

grep | head -5 from 10K (early term) — turbo 1.9x vs forked

lash-turbo

0.50ms

lash

0.33ms

grep -v | head -5 from 10K (early term) — turbo 2.3x vs forked

lash-turbo

0.40ms

lash

0.25ms

grep | tail -5 from 10K (ring buffer) — turbo 1.9x vs forked

lash-turbo

0.41ms

lash

0.22ms

grep | wc -l from 10K (count) — turbo 1.7x vs forked

lash-turbo

0.50ms

lash

0.23ms

grep -v | wc -l from 10K (count) — turbo 1.7x vs forked

lash-turbo

0.52ms

lash

0.33ms

grep | head -5 from 100K (early term) — turbo 2.7x vs forked

lash-turbo

0.40ms

lash

0.48ms

grep | tail -5 from 100K (ring buffer) — turbo 2.8x vs forked

lash-turbo

0.48ms

lash

0.65ms

grep | wc -l from 100K (count) — turbo 2.9x vs forked

lash-turbo

0.44ms

lash

0.66ms

tac | head -10 from 10K (rewrite) — turbo 1.3x vs forked

lash-turbo

0.10ms

lash

0.23ms

tac | tail -10 from 10K (rewrite) — turbo 2.2x vs forked

lash-turbo

0.41ms

lash

0.28ms

sort 10K lines — turbo 5.9x vs forked

lash-turbo

0.41ms

lash

1.8ms

grep pattern from 10K lines — turbo 1.0x vs forked

lash

0.28ms

lash-turbo

0.28ms

sort | grep | head from 10K — turbo 2.3x vs forked

lash-turbo

0.70ms

lash

2.3ms

single true (no-op baseline) — turbo 1.0x vs forked

lash

0.62ms

lash-turbo

0.62ms

2-stage true pipe (not optimizable) — turbo 1.0x vs forked

lash-turbo

0.08ms

lash

0.10ms

10-stage true pipe (not optimizable) — turbo 1.0x vs forked

lash

0.41ms

lash-turbo

0.42ms

awk pipe (not optimizable) — turbo 1.0x vs forked

lash-turbo

0.55ms

lash

0.53ms

100k lines through grep filter — turbo 1.0x vs forked

lash

0.68ms

lash-turbo

0.55ms

sort+head | awk | sort+head from 100K — turbo 4.6x vs forked

lash-turbo

4.9ms

lash

24ms

Prompt Rendering

Prompt rendering latency with starship.

starship prompt render

bash

5.3ms

lash

5.2ms

dash

5.9ms

zsh

6.0ms

6.4ms

fish

6.4ms

shell	median (ms)	startup (ms)	stddev (ms)	throughput (MB/s)
bash	5.85	0.51	0.57	—
lash	5.92	0.70	0.80	—
dash	6.23	0.35	0.77	—
zsh	6.65	0.70	0.72	—
sh	7.00	0.62	0.91	—
fish	13.99	7.56	1.67	—

starship prompt in git repo

dash

3.1ms

bash

3.2ms

3.4ms

zsh

3.3ms

lash

3.8ms

fish

4.0ms

shell	median (ms)	startup (ms)	stddev (ms)	throughput (MB/s)
dash	3.46	0.32	0.50	—
bash	3.76	0.54	0.67	—
sh	3.85	0.50	0.63	—
zsh	3.92	0.63	0.53	—
lash	4.55	0.76	0.66	—
fish	11.06	7.03	1.61	—

Protocol Overhead

Internal protocol performance (lash-direct only).

10k small lines (protocol batching stress)

lash-direct

0.06ms

16 x 1MB writes (large chunk throughput)

lash-direct

5541 MB/s

small lines then bulk data burst

lash-direct

1.8ms

16MB bulk data delivered to client

lash-direct

7628 MB/s

1GB bulk data delivered to client

lash-direct

9792 MB/s

~1MB as individual lines to client

lash-direct

0.46ms

How Turbo Mode Works

Turbo mode applies these optimizations automatically:

Passthrough stripping — removes identity operations so they never execute
Numeric sort key pre-computation — pre-computes keys in O(N) instead of parsing inside the comparator at O(N log N)
Streaming wc -l — counts newlines in the byte stream without collecting lines
C strtod for numeric conversion — calls C’s strtod directly, avoiding D’s to!double exception overhead
Fused operations — grep | head, grep | tail, and grep | wc run in a single pass over the data

Running Benchmarks

dub run :benchmarks

Options

Flag	Description
`--runs N`	Number of iterations per scenario
`--warmup N`	Warmup iterations before measurement
`--scenario S`	Run only the named scenario
`--json`	Output results in JSON format
`--verbose`	Print per-iteration timings

To reproduce these numbers:

dub run :benchmarks -- --runs 100 --warmup 10 --verbose