I have SP4 installed at home running W10 and on two 1080P monitors and I dont see this problem. SP4 under Windows 8.1 seems to work fine. As soon as I upgraded to Win 10, however, SP4 slowed to a crawl. Opening files took much longer than it did under W8.1, context menus are very slow as well. Even after updating to SP5 EV I have this issue.
Has anyone else experienced this?