game runs fine when I run from the IDE, but .exe gives frequent spikes

hi all. in xamarin/visual studio, when i build and run in both in debug/release modes, my game works runs perfectly smoothly (60 fps constantly). when i navigate to the debug/release folders though to run the .exe, i notice this gives me pretty random spikes from to 60 fps to under 20. any reasons why this could be?

thanks.