I have a 144hz monitor and gtk animations (for example, StackTransitionType.SLIDE_LEFT_RIGHT) on gnome (arch linux) are ~60 - 90 fps while on cinnamon (linux mint) it’s perfectly 144fps. Also, cinnamon has no lag after focusing and moving gtk window. Is it related to compositor?
Are you running latest Gnome Shell 40/41 with GTK4 and vulkan support? And which tools to you use to measure the screen refresh rate?
You cannot really compare whatever two different distributions do. Mint and Arch don’t have the same version of the Linux kernel, the Mesa driver, GNOME, GTK, or even the same compositor.
GTK animations are driven by the timing of the compositor, but it’s not clear cut: if the timing is slightly off, or if the toolkit misses the window because of some random CPU or I/O stall, you will end up with missed frames. There’s even the chance of the GPU going into a low powered state because of an updated kernel, and then taking a frame to go back.