Hardware:
Late 2016 MacBook Pro w/ TouchBar
LG Ultrafine 5K display
Setup:
Screen Sharing app connected to remote instance in the cloud
Problem:
Very slow response to keystrokes. There is no problem in other applications. The problem goes away if I disconnect the external display. The problem does not go away if I switch from WiFi to a hardwired Ethernet connection. I had thought this might be the monitor's shielding problem interfering with WiFi but no, it happens without WiFi. Truly perplexing!
Best Answer
Apple's implementation of VNC ScreenSharing often falls short, with significant lag regardless of whether
Adaptive Quality
is selected or not. A more robust 3rd-party solution like (the free) VNCViewer will provide you with fine-grained compression control, allowing workable VNC sessions over the tightest of bandwidth (e.g. through a shell tunnel to a remote server with really low upload speeds).