FPS changes on desktop from 60 to 30

I have Arch KDE with native Nvidia drivers. I also have multiple monitors. After updating the system, I started experiencing strange jumps in fps. For some time the frequency is 60, and then the frequency drops to 30 and remains there for some time. Mostly it starts falling when I move the windows. But when I launch games, the fps becomes 60 and nothing lags. I also noticed that after disabling the composer with the command “qdbus org.kde.KWin /Compositor suspend” the problem disappears. What could be the problem?

This sounds a lot like this bug. It seems like the most reliable workaround is to downgrade NVIDIA drivers to a known-good version.

The problem really turned out to be the driver version. Thank you!!!