Performance Problem That Has Me Totally Stumped

I have a strange and difficult (for me) problem to figure out. I have a user whose machine appears to have a performance problem. Every few days the mouse movement will get herky-jerky and things start to slow down. As soon as she reboots all is fine, until a few days later. When she has the problem I’ll look in task manager but I won’t see anything amiss, CPU, storage or network-wise. All looks normal to me, so I’m stumped.

This all started when I originally gave her a 3rd video monitor. I also gave her a different machine with a video card for the 3 monitors, but since then I’ve done numerous things with no improvement. That includes switching machines, changing video cards, removing the 3rd monitor and going back to 2, switching SSDs, running MalwareBytes, and adding memory (she’s using an SSD and has 16GB of memory). At this point I’m ready to give her a fresh OS and rebuild her configurations, but that’s a pain too.

Does anyone have other ideas? Should I try repairing Windows 10 Pro? Are you aware of things that might cause general slowdowns, not immediately obvious by reviewing what’s going on in task manager, and corrected by a reboot? Any help would be appreciated.

vgchat said:

What you should do then is have her start Resource Monitor and you'll have a chance to see what's going on from there.

I'll do that. What would you expect to see there when things are wonky?

Any other suggestions?