Slow response in IDE

Prior to AS v2.0 the response in the IDE (editor, object selection from a package list etc) was great, just as I would expect. Then sometime after upgrading from v2.0, until v2.2.3, the response has suddenly become very sluggish. Scrolling down to select a layout, class or any other artifact, the IDE hangs for up to 5 seconds before responding. Same when editing source code, layout or any other artifact. No other app on my PC (Win10, 64 bit, 16 gig ram, fast Intel I5 processor, gobs of disc space etc) behaves this way. Interestingly, build times are not affected, still pretty quick. I have set custom vm options to larger values. This has had no effect. Discs are not fragmented.
I have researched this behaviour and found nothing, so am assuming it's a local issue.
Does anyone have a suggestion for fixing this behaviour?

No, but that's my next step. Thanks for your response. Still trying to understand the reason for the degrading performance. One thought might be large log files.