Benchmarks

These benchmarks are not intended to say one library is better than another, only to provide some rough idea of performance as a reference.

To reproduce these tables:

pnpm bench            # the tables below
pnpm bench:vs [rev]   # this working tree against another revision, to check a change
pnpm bench:size       # bytes emitted rather than time

All benchmark data below was produced on a base-model M5 Macbook Air

Relative speed

@itsy/html is 1.00 in every column. Higher is faster, meaning 1.33 is a third faster and 0.25 is four times slower.

renderer	one <a>	one element	nested page	1000 rows	escape-heavy	overall
no escaping	9.34	3.94	2.54	1.95	428.87	9.51
hand-written	1.43	1.42	1.00	1.17	1.09	1.21
@itsy/html	1.00	1.00	1.00	1.00	1.00	1.00
hono/html	0.74	0.76	0.58	0.69	0.81	0.71
ghtml	0.72	0.78	0.57	0.67	0.83	0.71
htm + preact-render-to-string	0.34	0.28	0.28	0.25	1.23	0.39
lit + @lit-labs/ssr	0.17	0.18	0.15	0.17	0.46	0.20

Absolute time per render

Lower is faster.

renderer	one <a>	one element	nested page	1000 rows	escape-heavy
no escaping	12.1 ns	44.3 ns	0.96 µs	102 µs	0.01 µs
hand-written	78.5 ns	123 ns	2.45 µs	168 µs	2.15 µs
@itsy/html	113 ns	174 ns	2.45 µs	198 µs	2.35 µs
hono/html	153 ns	230 ns	4.22 µs	286 µs	2.92 µs
ghtml	156 ns	224 ns	4.28 µs	296 µs	2.83 µs
htm + preact-render-to-string	330 ns	613 ns	8.66 µs	780 µs	1.92 µs
lit + @lit-labs/ssr	657 ns	953 ns	16.3 µs	1195 µs	5.09 µs

html vs trusted performance

trusted is a more performant export that removes escaping

renderer	one <a>	one element	nested page	1000 rows	plain text	overall
no escaping	5.91	2.77	1.91	1.55	8.98	3.37
@itsy/html trusted	2.12	1.62	1.71	1.48	2.53	1.86
hand-written	2.26	2.00	1.30	1.34	1.72	1.69
@itsy/html	1.00	1.00	1.00	1.00	1.00	1.00

renderer	one <a>	one element	nested page	1000 rows	plain text
no escaping	12.4 ns	44.8 ns	0.90 µs	96.5 µs	6.06 ns
@itsy/html trusted	34.7 ns	76.6 ns	1.00 µs	101 µs	21.5 ns
hand-written	32.5 ns	61.9 ns	1.31 µs	112 µs	31.7 ns
@itsy/html	73.5 ns	124 ns	1.71 µs	150 µs	54.4 ns

Benchmark test descriptions

Rendered from a list of 1000 products whose names hold & and ", and whose links hold & — ordinary data that still has to be escaped.

column	what it renders
one <a>	a single link: one URL attribute, one class, one text value
one element	one <article> with five values in it, no URL attribute
nested page	a nav and a list, built from templates nested three deep
1000 rows	a table, 1000 rows of four cells, each row nesting a link template
escape-heavy	760 characters of nothing but <, >, &, " and '

The escape-heavy column is the worst case for an escaper, not a realistic page. Text with nothing to escape should be the fastest path for every renderer.

The two reference points

hand-written is a plain template literal with an esc() call around each value, using the same escaper @itsy/html uses. It has no scanner, no context, no URL guard and allocates no Html, so it is the 'speed floor' and not a typical performance example.

no escaping is the same template literal with the esc() calls taken out. It is meant to be a reference for the absolute fastest the test machine is performing at.