Refresh rate is slow on my Raspberry pi

[bco2135]

I installed cinnamon on my raspberry pi 4 (Model B) not long ago and ever since I installed it, it's been really slow. When I drag a window its position only updates every like 300 milliseconds. I looked at the System Monitor and it usually only takes 30% - 55% of the CPU and 45% of the Memory. Is there any way to speed up the refresh rate? (Also it might be the size of my monitor 1920 x 1080 but I'm not sure)