This repo tries to assess Rust arg parsing performance.

We currently compare:

Name	Style	Notes
No-op	N/A	N/A
argh	derive
bpaf	Combinatoric or derive
clap_lex	Imperative	No help generation
clap	Builder or derive	Color, suggested fixes, completions
gumdrop	derive
lexopt	Imperative	No help generation
pico-args	Imperative	No help generation
xflags	proc-macro

See also an examination of design trade offs

Note: any non-performance comparison is meant to provide context for what you gain/lose with each crate's overhead. For a full comparison, see each parser docs

Results

Name	Overhead (release)	Build (debug)	Parse (release)	Invalid UTF-8	Downloads	Version
null	0 KiB	163ms (full) 115ms (incremental)	1ms	Y	-	-
argh	38 KiB	4s (full) 138ms (incremental)	2ms	N		v0.1.14
bpaf	256 KiB	831ms (full) 137ms (incremental)	2ms	Y		v0.9.23
bpaf_derive	253 KiB	4s (full) 140ms (incremental)	2ms	Y		v0.9.23
clap	574 KiB	3s (full) 170ms (incremental)	2ms	Y		v4.5.60
clap-minimal	377 KiB	2s (full) 155ms (incremental)	2ms	Y		v4.5.60
clap_derive	596 KiB	4s (full) 182ms (incremental)	2ms	Y		v4.5.60
clap_lex	28 KiB	336ms (full) 129ms (incremental)	2ms	Y		v1.0.0
gumdrop	28 KiB	2s (full) 135ms (incremental)	1ms	N		v0.8.1
lexopt	37 KiB	329ms (full) 124ms (incremental)	2ms	Y		v0.3.2
pico-args	24 KiB	300ms (full) 123ms (incremental)	2ms	Y		v0.5.0
xflags	23 KiB	539ms (full) 123ms (incremental)	1ms	Y		v0.3.2

System: Linux 6.17.9-76061709-generic (x86_64), rustc 1.94.0 (4a4ef493e 2026-03-02) w/ -j 8

Notes:

• Overhead will be lower if your application shares dependencies with your argument parsing library.

Running the Benchmarks

$ ./bench.py
$ ./format.py

To be included, the crate needs meet one of the following criteria:

• 10k+ recent downloads
• Unique API design

Special Thanks

• RazrFalcon for creating the initial benchmarks
• djc for inspiration with template-benchmarks-rs
• sharkdp for hyperfine