While I run around ingame with an FPS overlay (as well as the ingame graphics setting open), it displays a constant 60. However, I notice that my game still drops in frames at times despite the number staying at 60.

I noticed that this happens with full screen windowed. It works fine in normal full screen. I prefer to run this game in full screen windowed since I play with dual monitors; does anyone have any ideas to resolve this or is this a known problem with the game's optimization?

I play with Vsync enabled.