MacBook Pro (2014) with two external 4K screens here: Got glitches (some areas of the screen sometimes look like rendered memory corruption). When I scale the

MacBook Pro (2014) with two external 4K screens here: Got glitches (some areas of the screen sometimes look like rendered memory corruption). When I scale the external monitors’ resolution from 1920x1080 Retina to 2560x1440 Retina per monitor, macOS lags heavily and freezes. Sometimes, after a few minutes, it recovers and seems responsive. Then I drag a window and it becomes unresponsive again to the point where it won’t recover and only a hard reboot helps. Upside: With Metal 2 the fan stays quieter. I can use two 4K screens and won’t get deaf from a jet turbine on my desk. Before High Sierra I connected at most one 4K screen and occasionally disconnected it because the built-in dedicated graphics card got really hot and caused the fan to run at high speeds.