Comment # 13 on bug 965564 from Thomas Blume

(In reply to Ludwig Nussel from comment #9)
> The upstream discussion about that feature is here:
> https://lists.freedesktop.org/archives/systemd-devel/2015-November/035006.
> html
> 
> Commits:
> https://github.com/systemd/systemd/commit/
> 0af20ea2ee2af2bcf2258e7a8e1a13181a6a75d6
> https://github.com/systemd/systemd/commit/
> 9ded9cd14cc03c67291b10a5c42ce5094ba0912f

systemd 228 has these defaults (/etc/systemd/system.conf):

#DefaultTasksMax=512

I guess this is the bottleneck.
Can't you just set it to a higher value for the build machines?