Modern CPUs are powerful devices which can run most applications without difficulty, but run enough processes at the same time and your performance will soon fall away.
Project Mercury (64-bit version) is a freeware tool which automatically optimizes process priorities and RAM usage to ensure your active application always has the maximum system resources.
Setup is easy, because there isn’t any. Download the tiny executable, run it and Project Mercury immediately goes to work.
Start using any application and its priority gets boosted to "Above Normal". If you’re running lots of processes and they’re fighting over core time, your active program will now get a greater share.
Minimize that program later and Project Mercury reduces its priority, which means it won’t grab quite as many resources while running in the background.