Why does my game run at a slower FPS windowed versus full screen?

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:bust_in_silhouette: Asked By Diet Estus

I notice that my game oscillates between 58 and 59 FPS when windowed in its native resolution of 640x360, but runs at a smooth 60 FPS when in full screen.

This causes there to be slight stuttering on my background in windowed mode, but not in full screen.

Why might this be and how can I fix it?