8.1: High disk activity makes it unusable

After updating to 8.1 (the update process went fine - no such issue on 8), at seemingly random moments, hard disk activity goes up the wall, essentially making the system unusable for 3-4 minutes. Here is a pic of the task manager (it can go a lot higher than 5.3 MB/s):




The Device Manager shows no driver issues/conflicts. The only differences from 8, are all those WAN miniport entries. They weren't there in 8 and I don't know what they are. (edit: after a restart, they are now gone...)





I'm literally one step before going back to Windows 7... thanks for any kind of help.

About the disk activity, always happens here after any OS install\upgrade, so many things can be going on (cleaning of temp files, rebuilding index, defrag, defender scan, other maintenance, scheduled this&that, automatic updates + drivers installing and more).

Before doing anything (always a risk of breaking something), maybe give it a few days of normal use, tolerating the lags, and see if it calms down. If still a problem, one can (usually) find the exact cause and change some settings. Good luck.

Thanks. I'll wait a bit more. Also, tried to eliminate some of these reasons (disabled scheduled defragmentation, waited for indexing to complete, disabled Defender [there's another security application, the same I've always used].