Why the mouse in Payday 2 feels so heavy?

The game

I guess you could change your mouse sensitivity.

It's the gold bags + heavy armor.

Vertical sync is probably the culprit here.Try disabling it, AND if that does not work try setting a frame limit below your usually frame rate eg: you have steady 62 fps, set limit to 60.
If that does not help I don' t know.

Stop feeding it so much cheese

Low FPS maybe?

Lowering the resolution worked for me.

There is a fix
If you have an nvidia card go to the driver's control panel>manage 3d settings>Program settings (choose Payday)>maximum pre-rendered frames= change it to 1
It also goes without saying that you must disable V-sync in the game's settings

For AMD I have no idea :P

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Approved by Hatless ZombieHunter

It's really a rat from Stephen King's Graveyard Shift, from the lower levels.