PSA: Use fullscreen mode, not borderless (performance issue)

This type of jump, and the mention of "60 fps" windowed suggests it is more a vsync issue more than anything. What is the refresh rate of the monitor you are using? Going from borderless to fullscreen will not yield this kind of increase unless something else is at play. In windowed mode, games tend to often times be restricted by vsync sometimes. For example, I have BF 2042 set in the Nvidia control panel to run without any cap on framerate. If I play in windowed mode however, my framerate will in fact cap to my Gsync set limit of 117FPS. This is true in any game I play. The point here is that there are a lot of caveats to this. Your increase is likely due to you just not understanding how this works and little or nothing at all to do with the game actually performing better in full screen.

Full screen though is typically recommended in games, not just because of the above issue but because some games get less input lag in fullscreen as well. For competitive play, fullscreen is always recommended.