If you use a logitech mouse, you may need to install an add on called “SmoothWheel” or “Yet Another Smooth Scrolling”. I’ve dealt with a lot of lagginess from FF and logitech mice WRT scroll wheels. Try SmoothWheel first and see if it helps.
Checked everything, batteries, transceiver, KVM, location, drivers, sw, etc.
Just when I was about to give up, I popped open the battery compartment, and shook the heck out of the thing while it was upside down.
Nothing came out, but something was rattling around inside.
It still rattles when picked up, but it works fine, allowing me to go back to using the KVM setup I had before the problem started, although I'm gentle, just in case, when flipping it over to turn it off or on.