Another Windows 10 feature. Seen it myself, so rest assured it's not you or your equipment. After the Creator's update, if your CPU usage gets too high, some input devices will be starved for updates, although the machine will still be reading the input, so you get the lagging.
Only guaranteed solution I've seen is to use an input device such as a PS/2 mouse that gets it's own interrupt. This isn't a solution, it's a band aid. The fix will have to come from Redmond or possibly updated drivers.