IdleOn will now properly close when exited, and will not slow your computer down after failing to close (since it won't fail to close anymore)

If you just care about playing, you can stop reading and GO PLAY!! :D
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Are you the Rick of your 'Rick and Morty' viewer group? Do you want an in-depth, detailed explanation of what was happening? Then keep reading!

In-depth explanation of the issue
While the main container process and child utility processes (e.g. for sound and network) closed correctly when exiting the game, the child renderer process (that displays the game) would sometimes remain open and continue trying to draw and run the game: hence the high CPU & memory usage.
I've put the renderer process in a sandbox now so it should require the main process & now should be required to close when the main process ends. This way, when you exit the game, you'll never end up in a situation like before where the child renderer process remains open"