Coincidentally, I just found this going on, again. I noticed it because my bluetooth keyboard was stuttering and missing keystrokes. task manager is showing 100% ongoing and as usual, OneDrive sync and Windows search indexer are at the top of the pile.
Pausing the OneDrive sync returns everything to normal levels. I am rerunning the troubleshooter but have only had it stop this impact 1 time of the last 5 times I have used it. Even a reboot does not fix this and it returns once the system is rebooted and back to normal idling tasks.