I was experiencing this issue as well, where the system would lock up or stutter for 1-2 seconds (keyboard input lag, screen not updating, etc). This would happen all the time, but most notably while I was using Chrome or switching between apps. Disabling font smoothing made no difference, and neither did PRAM or NVRAM reset (does that ever work for anything at all?). Disabling iCloud and other sync services (dropbox, whatever else) also did nothing.
As soon as I disabled graphics switching, everything was OK.
I am not sure what that means for Apple: Does the graphics driver need to be fixed? Is the video card slow to start up? Is the T2 chip somehow involved in brokering or abstracting hardware communications, leading to a slow down? I have no idea. However, Google Chrome (especially with hardware acceleration enabled) is indeed very aggressive with gpu resources and often triggers the video card, which would explain why I often saw this problem while using Chrome.
See this thread for additional insight:
https://forums.macrumors.com/thread...e-issue-automatic-graphics-switching.2217231/
Other notes:
1. I did not have this problem with my MacBook Pro 15" 2017. I'm sure there was a slight delay when graphics were switching, but it was never very noticeable.
2. I only see the issue on my 16" when I am running without an external monitor connected. This makes sense because video card switching is disabled whenever an external monitor is connected.
3. I strongly suspect that all MacBook Pro 16" owners are having this issue, but (a) many are using external monitors or (b) many are simply not sensitive to the system stutter
4. I also had stuttering problems on a MacBook Pro 15" 2018 about a year ago. On reflection, that machine probably had the same video card problem as the 16" (although I did not think to troubleshoot this at the time). I returned that machine within the 14-day window. Given that the problem did not occur on my 15" 2017, I do wonder if the T2 chip is somehow impacting graphics switching on the 2018 and beyond machines. (Total speculation, as there could be other issues with the video card hardware or drivers.)
5. I tried reproducing the stutter in the Apple store, however I believe those machines have graphics switching disabled while the computers are running in demo mode (the system stutter therefore never manifests).
6. I originally thought that this was a problem with the bluetooth driver on the machine. I say this because noticed that anytime my system stuttered, there would be an error in my console.app indicating "Sandbox: bluetoothd(152) deny(1) mach-lookup com.apple.server.bluetooth". I suspected that this bluetooth error was causing the machine to hang up while the system sorted itself out. My machine stutters have gone away after disabling the graphics switching, but the bluetooth errors still show up in my console.app. The errors are annoying, but they don't seem to be causing any disruption. I actually had a thread for that at
https://forums.macrumors.com/thread...-2019-16.2221046/?post=28171906#post-28171906
If you mostly run without an external monitor, I recommend manually toggling your video card on or off until Apple sorts this out (wouldn't hold your breath on that happening anytime soon). You can use
https://gfx.io/ -- the app has not been updated for a while, but nevertheless works great (kudos to the dev on that one). You can also of course just disable graphics switching, and leave your dedicated video card running all of the time.
Hope this helps.
