after every build the processtree killer will kick off.

on my reasonably powererful windows laptop with lots of stuff open this can take 700+ms

This impacts every unit test and has been the cause of having to disable some tests on windows - which is not great.

The code needs to be improved.

One way to do this is to pass the list of environment variables to check down to C++ and only return the pids for them rather then every pid - which is then parsed and put into a map (which consumes over half of the time)

I have ~490 processes running,