Speed ​​up compilation times with a multicore machine

I run a build server for an open source project and it often has to rebuild huge libraries that take at least 30 minutes to build an Intel i7 processor with an 8-lane core, maxing out after a few hours.

Lately I was wondering if there are relatively cheap dedicated multi-core boards I could use to speed up compilation times, but my google-fu couldn't find anything other than Parallella on Kickstarter, googling which doesn't seem to fit with many the results of my use.

Do you know of any cheap tiered boards that I could use to speed up compilation of C / C ++ software?

Cheap on-demand services can provide services that provide multi-core / distributed compilation, but they are much less favorable as you will need to check that their compilers, libraries, and are not yet genuine so that they do not introduce any backdoors in any code that you compile, which is rather difficult to check. That is why I am primarily looking for multiprocessor boards on which I can handle the compilation task myself.