Performance BUG? Warning: Hitch on async loading of Texture2D

Ever since i upgraded my 4.18 VR project to 4.19, i started to get these warnings in my packaged game. I get terrible lag, and this may be the cause. In 4.18 it was running fine.

I switched out all SS logic to use the new PD. So i run with SS=100 and PD=1 and made sure i have SS=1 in steamvr too. I also used VIS command to make sure the actual rendered textures are the currect sizes (2160x1200 * 1.4 = ~3024x1680), so the resolution is the same as i was on 4.18.

I’ve attached my game log. My rig is i7-4970, 1080ti, 32gb ram. Latest nvidia drivers, even though the log says unknown for some reason.

Any suggestions? Have i maybe hit a bug?[link text][1]

Also see how i looks in the profiler. As you can see from the first screenshot

, both game and renderthread are within 10-11ms, but as you can see from the other screenshots, there are also other correlating stats that spike, that might be related.

While looking for hints to why my game hitches, i noticed quite a few changes to async loading, and specifically these new settings:

New: Added Level Streaming CVars to customize streaming for your project. These all default to enabled, but can be disabled to make different trade offs for memory and level loading performance.
“s.ForceGCAfterLevelStreamedOut” - Whether to force a GC after levels are streamed out to instantly reclaim the memory, at the cost of a hitch. Defaults to on.
“s.ContinuouslyIncrementalGCWhileLevelsPendingPurge” - Whether to repeatedly kick off incremental GC when there are levels still waiting to be purged. Defaults to on.
“s.AllowLevelRequestsWhileAsyncLoadingInMatch” - Enables level streaming requests while async loading (of anything) while the match is already in progress and no loading screen is up. Defaults to on.
Added several new stats for potentially slow code.
Added SCOPE_CYCLE_UOBJECT macro, instead of using Scope Cycle Counter UObject directly.

I wonder how this was working internally in 4.18 compared to 4.19?


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I noticed that if i run with stat startfile (for profiling) i get the hitching nonstop, but without it, i only get some hitching very rarely, and only for a second or two.

Wild guess is that it’s related to: UE-57976

Hi @Jeff A :diamonds::diamonds:, see my comment below. I have a feeling this is related.

Another update. Today i apparently get hitching nonstop no matter what. Its still worse with stat startfile running, but i get significantly more than i got the other day. This effectively means that my game is unplayable. Can we assume Epic knows about this or what can be done?