That changes things a bit.
Run a benchmark test. Also, try to verify that your update completed successfully, failed/half-complete updates can do really weird things sometimes.
What's your GPU and have you tried running anything to look for artifacting and lag? Suspecting either a GPU failure or just a burned-out monitor here.
When not on here (pretty often I expect) I can be found writing on wikiHow under the same username (because wikis!) and gaming (because PCMR and all that).