Multi-threaded run does not scale up performance as intended

[rootatkali]

The issue is replicated on most, but not all, machines.

[rootatkali]

Caused by #26

[oriyadid]

I believe I am able to reproduce this on my machine (Linux, OpenJDK 17). Just to confirm I am seeing the same behaviour, when running in non-headless mode do you also see the war count stuttering rather than incrementing smoothly as it would with a single thread? It also appears to be slower than just one thread for me.