General Setup

Install LLVM/Clang

Clang is a faster compiler than the default GCC. It produces binary as fast, or faster than GCC. To set up clang,

run emerge llvm clang

and add these to lines to the top of your /etc/make.conf file

CC=/usr/bin/clang
CXX=/usr/bin/clang++

If a package fails to compile with clang, you can comment out those lines, and recompile the package with GCC.