I hadn't thought about using the Reset. I've started by deleting the webpage previews, along with Cache & History (which I delete periodically anyway).
I don't use AutoFill (I use 1Password); so nothing to delete there.
I downsized the Database storage to 5 mb (from 10), but I don't have any db that shows up in that window. (Is there one somewhere?)
Web site icons are only elements I haven't yet deleted. (I admit to liking them.) But, if these slow-downs, and periodic lock-ups, continue, then I'll delete them & let them re-establish.
I am curious about why I also get errors during the loading. [example - Loaded 127 of 129 pages (2 errors) ] What causes that to happen?