Hey everyone, I updated my project from 5.5 to 5.6 and suddenly get bad input latency on my ROG Ally (Extreme Z) testing device when capping to 30fps. At first I thought it was just playing at 30fps but I started the last build from my 5.5 project again and the added latency wasn’t there.
Tapping through menus and controlling the player feels sluggish and delayed.
So I looked at the project settings and there’s nothing strange with fixed/smooth framerate or anything other obvious in the 5.6 project.
And of course the ROG Ally is not a performance monster but the latency wasn’t there in 5.5.
The one thing I could see is that the CPU Util of the ROG Ally went from 11% (UE5.5) to 28% (UE5.6) in the same scene.
Nanite is in use, no difference if i enable/disable lumen.
Has anybody had a similar problem? Any help would be much appreciated.
Checking around the community, there are isolated mentions about input latency under certain conditions, but none as specific as yours. Some users have tested around with Low Latency Frame Syncing functionality, with different results. You can check the UE doc for said features below:
There’s also a thread with a similar issue to yours, please check their findings for your scenario:
Hey thanks for your quick reply, I tried the settings you linked and while they may have helped a bit I think the true problem here is using an external frame cap.
I used nvidia app on my PC and the Asus provided framecap on the ROG Ally to cap to 30fps and in both cases there was a lot additional input lag on my UE5.6 build.
The 5.5 build is not showing these results.
Also tried without external framecap and instead tested with t.MaxFPS 30. This results in no additional lag in 5.5 or 5.6.
So the problem must be how UE 5.6 and external framecapping interact.
So I found the solution. I looked at everything I changed from going from UE 5.5 to 5.6.
I added the new AMD FSR4 Plugin and thought it was turned off all the way in project settings (I activate it with console commands later if the user chooses it). So here is the screenshot of the project settings where I had “enabled” off already. But: Frame Generation was enabled by default while I thought having FSR4 disabled in general settings above would also turn off frame generation below, regardless if it was checked.
So I learned something new: FSR frame generation was enabled even though I had general FSR turned off above. And the horrible delay was probably using frame gen on a locked 30fps using external frame capping.
I hope if someone has the same problem they will see this post
