Possible solutions to fix mouse input lag and/or inconsistent framepacing

[bobbie424242]

For people having mouse input lag or framepacing issues, several possible workarounds.
These workarounds are for when no setting you change in-game can fix it:

- unlock fps with the "cl_engineFPS -1" command on the console (tilde key) combined with "Options > Display > Open video settings.. > Vertical Sync" disabled. You can also try setting a high value for cl_engineFPS to cap it (for example 200).

- use RTSS to limit framerate of doom.exe to your monitor refresh rate - 1 (ie 59 on a 60 Hz monitor) combined with with "Options > Display > Open video settings.. > Vertical Sync" disabled (and if you want to go fancy, force V-sync in NVIDIA CP for doom.exe).

- change "Options > Display > Open video settings... > Graphics API" to "D3D11" and enable "Vertical Sync". Restart the game for the change to take effect

- disable VRR for your monitor (on NVIDIA this is done in the Control Panel, can be done globally or per game) and enable "Options > Display > Open video settings.. > Vertical Sync"

The Kex engine has very weird handling behaviour of mouse input vs framerate / monitor refresh rate / v-sync / VRR / game target fps (cl_engineFPS). Potentially more problematic on 60Hz monitors.
Even more curious is that the mouse sensitivity seems to be dependant on target framerate (cl_engineFPS)