Currently Envoy uses zlib as a compression library.
zlib-ng is a fork that hosts several 3rd-party
contributions containing new optimizations. Those optimizations are considered useful for
improving compression performance.
Envoy can be built to use zlib-ng instead of regular
zlib by using
--define zlib=ng Bazel option. The relevant build options
used to build zlib-ng can be evaluated in here. Currently, this option is only available on Linux.