Questions related to benchmark results in README file

[ksolana]

1. Is v1.5.6 slower than v1.5.1?
   As per https://github.com/facebook/zstd/tree/dev?tab=readme-ov-file#benchmarks the results for v1.5.6 is worse than v1.5.1 https://github.com/facebook/zstd/blob/v1.5.1/README.md at --fast=3.

zstd 1.5.1 --fast=3 	2.239 	670 MB/s
zstd 1.5.6 --fast=3 	2.239 	650 MB/s

zstd 1.5.1 -1 	2.887 	530 MB/s
zstd 1.5.6 -1 	2.887 	510 MB/s

Is it just noise level?

2. Why are the results collected using a very old version of gcc? The latest gcc-14 is 5 years ahead of the one used in benchmarking.

[Cyan4973]

Is it just noise level?

Yes, most likely

Why are the results collected using a very old version of gcc?

The system used for this benchmark was running on Ubuntu 20.04, which default compiler is gcc-9.
This will be changed in the next update,
using most likely the default compiler of Ubuntu 24.04.