Compilation is very slow
Found the answer on anoter thread on this forum. (Slow Build)
Exclude the compiler directory from the virus scanner:
C:\Ac6\SystemWorkbench\plugins\fr.ac6.mcu.externaltools.arm-none.win32_1.15.0.201708311556\tools
Now the compilation time takes:
10:53:44 Build Finished (took 1m:4s.52ms)
My cpu load is never higher than 24% so there is room for improvement