I have noticeable input lag on my Pi4 4GB when using vc4-fkms-v3d driver which is completely gone when I use frame buffer. It feel like at least one frame of additional lag.
At first I thought it is usbhit.mousepoll issue with my wireless mouse I use for Pi but this was not it. The lag is there no matter of this or any other setting, mouse and monitor used and is completely gone when I comment driver. I did rpi-update twice, including today before posting this.
For my use this is actually non-issue as I do not care about 3D or playing games. Chromium works great, even better than with hardware acceleration because it made system unresponsive when playing videos. Videos plays great without this driver in VLC, even 110Mbps H264 sample so that is great. But I guess that this kills the idea of ever using this computer to play any games which require hardware acceleration to be present and generally an issue for most users who mind not come up with the idea to disable video driver or actually test if it works better that way.
This is my first Pi and I do not use Linux other than on Pi so I do not know if this is expected behavior or not.
Is there a way to configure video driver without input lag? Not having this driver (yes, it is completely unusable as it is!) reduces advertised functionality of this device...