Mouse lag with external dispaly

Question

Level 1

11 points

Mouse lag with external dispaly

There was a prior thread on this spanning many years/models with the same problem and no real solution...what was suggested (moving cables around) hasn't helped me. What I have:

Latest generation 16" MBP
v2 magic keyboard and trackpad
Dell 28" monitor running via USB-C
Running in clamshell mode

I have severe mouse lag making machine unusable w/ external display (despite many reviews touting this as an A-O-K monitor for MBP). Mouse and keyboard also lose connection a lot more often than prior v1 devices. Makes me sad for upgrading. :-(

What I've tried with no success (desperate last ditch things included):

Make sure all updates are applied
No other running apps / disable everything I can
Zap PRAM/NVRAM and reset SMC
Move USB-C cable away from any other cable/device/power
Move USB-C cable to different side/ports

Really bummed I went with this setup as an "ideal" coding solution based on numerous expert reviews and it just isn't happy here. Not sure what else to try. I can barely scroll this page to post due to mouse being so laggy/inconsistent. Help?

Posted on Jan 9, 2020 11:33 AM

Reply

Answer 1

dwb

Level 7

33,214 points

Jan 9, 2020 11:39 AM in response to DeadlySyn

I've not paid much attention to the 16" MBP (other than to try out the keyboard) so I don't know where the BT antenna is. Check out the Internet for tear articles (there were a couple) and see where it is. Then try orienting the computer so the antenna is close to the keyboard/pad while at the same time as far away from the cables as possible. The problem has to be interference so this is the direction you want to work on. A side question, even though you'd ideally be in clamshell mode, is there improvement if the notebook is open?

Reply

Answer 2

Jan 9, 2020 12:10 PM in response to DeadlySyn

Cursor-potion updates happen at low CPU priority.

So mouse lag is most often caused by CPU problems or anti-Virus software. Use Activity monitor to see if anything is obviously hogging the CPU.

Reply

Answer 3

DeadlySyn Author

Level 1

11 points

Jan 9, 2020 7:56 PM in response to DeadlySyn

Thanks for the ideas folks... Quick update for posterity:

From the prior threads, I suspected antenna proximity as well. No joy unfortunately, the issue persisted even with the laptop moved beside the keyboard and trackpad (sitting right in front). Behavior was the same whether in clamshell mode or open (I opened it up when trying it in front of the accessories). I moved everything on the desk to the opposite side of the laptop and rerouted all cables without improvement as well.

CPU was what I suspected from the lag, but after killing all running apps (even disabling spotlight indexing), stopping anything I can in the menu bar, doing a couple reboots, watching activity manager to verify nothing was hogging CPU it still persisted.

Despite using a well-reviewed but not over-priced USB-C cable, I started to suspect that the lag was somehow coming from perf hit of driving the scaled display. I tried moving the cable from different sides (also partially to get as far away from power cables as possible) without any change at first. However, in display properties when I manually turned the monitor off/on I got some different options to optimize my display. Re-plugged, and lost them. Powered off/on, came back...

I'm not sure what's happening exactly (got distracted with work at that point), but it seems to have been related to some sort of monitor sync issue in my case. This is (I guess) why it's worked fine for a couple weeks without all this trickery. Not sure what got it out of sync, if it's hardware/driver/etc, but it's easy enough to just power the monitor off/on. Annoying in that it doesn't seem like a real fix, but definitely seems like the root cause in my case.

Reply

Mouse lag with external dispaly

Similar questions