Optimize WebCrypto bytes-to-hex.

[davidlehn]

• Improvement depends on number of digests performed.
• Browser:
  • Precompute a byte-to-hex table.
  • ~4-9% improvement overall using improved algorithm in Node.js.
  • Browsers should see similar speedup. Node.js normally will use the method below.
• Node.js:
  • Use native Buffer.from(...).toString('hex') conversion.
  • ~5-12% improvement overall.
  • The non-WebCrypto MessageDigest on Node.js is still faster.

Getting consistent benchmarks on a non-idle system for the async webcrypto code is difficult. Numbers below can be +/-2%.

bytes-to-hex

Comparison

Test	'base'	'precompute'	'buffer'
#manifest#block-1	4709.85	5.53%	5.36%
#manifest#block-2	863.09	8.77%	11.26%
#manifest#block-10	189.20	6.40%	7.34%
#manifest#block-100	18.97	9.89%	12.30%
#manifest#block-1000	1.97	4.21%	5.90%

base ops/s and relative difference (higher is better)

Environment

Key	Values
Label	'base', 'precompute', 'buffer'
Arch	x64
CPU	Intel(R) Core(TM) i7-4790K CPU @ 4.00GHz
CPUs	8
Platform	linux
Runtime	Node.js
Runtime Version	v16.19.1
Comment	'bytes-to-hex'