Alt+Tab makes the game do strange stuff

What this problem is related to? (e.g. Game / Launcher / Website / etc. ): The game

Describe the problem: The longer Alt+Tab goes, the less initial FPS will be after the game becomes active after the alt+tab. If i go for a really long Alt+Tab, my game drops its fps to the floor and slowly gains it to a normal values. It feels like something is being loaded every time the game goes Alt+Tab, and the more the Alt+Tab goes, the more of that “something” the game needs to lead after it becomes active.

What was the expected behavior?:

List the steps that occurred before the problem appeared:

Can you reproduce the problem?: Yes

Operating System, Browser version, Antivirus, or any other related platform information (if relevant):

Screenshots/Videos (if available):

I’ve just noticed that happens not everywhere. That happened to me on the little mushroom village with the Pudding.