Fastest Single-Unit Compile CPU

[Kai Song]

Hello,

I seek advice on good CPUs and CPU benches that allow me finding a good CPU
for compiling a single c++ compile unit with the G++ compiler.

Background:
- Many features in my code only work exclusively with G++, hence I do not
care in other compilers.
- I sometimes need recompilation for a single sign flip in the project and
that would take several minutes. Throwing (proportionately) money at it in
order to make that quicker could be advantageous.
- Splitting of compile units into many smaller ones is impossible due to
the code being compiled is generated from a script that e.g. depends on a
sign flip in the project.
- Benchmarks such as the Firefox compilation use parallelism. I don't care
about that.

What should I look for?