With new official "remaster" sourceport, the game defaults m_forward to 0, even though the original and other Quake engine based games (including Source engine) by default use m_forward 1, which might make the aiming feel laggy in the new version.
The new command for mouse sensitivity is now "cl_sensitivity" and the config file is kexengine.cfg inside %USERPROFILE%\Saved Games\Nightdive Studios\Quake