What is RHIT and why UE 4.21 runs so slow on mobile?

Hi all!

I’ve noticed, that our project started to run very slow on medium devices since 4.21 version.
Here are some stats

Resolution - 720p on every device. HDR enabled.

Xperia XA (Mali-T860 MP2) (Post process and HUD disabled):

Mi Max 2 (Adreno 506):

Galaxy Note 8 (MaliG71 MP20):

I do not get 60fps even on galaxy note 8.

UnitGraph shows very high RHIT on some devices. What is RHIT and how do we make it run faster? Or any other advice about it?

A long time ago (ue 4.7, 4.8) we used to create games with Mobile HDR which runs with 25-30 fps on galaxy s3 - s4. Now it is not possible to get 30fps on galaxy s3 even without hdr… I know it is an old devices and unreal gets more features, but there are very heavy features that have to be turned off. But how?

I also found this… problem, and, actually, was able to speed up mobile rendering abit :slight_smile: Maybe it will be helpfull for you:

  1. Turn off HZBOcclusion - “r.HZBOcclusion=0”, it eats way too much
  2. If you don’t need occlusion culling - turn it off completely, you will get few additional milliseconds
  3. Use EmulatedUBs - “OpenGL.UseEmulatedUBs=1”

Don’t use textures (especially lightmaps) with resolution > 2048. Just… don’t :slight_smile: By mistake i had lifhtmap with resolution 4k, it ate about 10 FPS (42->32).
Check material complexity, you definitely don’t want to have anything red, especially with high overdraw.
For static meshes (if > 2) try to use HISMs, they help alot.
Use only static shadows, try to not use any stationary directional lights, they slower.
Of cource turn off PostProcessing and AA, they will kill FPS.

Using those simple configurations and rules, i was able to get ~32-40FPS on device with Mali-T860 MP2 and fully PBR scene with visible static triangles ~35-40k, and skinned meshes triangles ~80-140k.

If i’ll remember anything else, i’ll add.

@Astartis, Thank you! But those advices did not help me.

I tried to build very simple project on 4.21 without any additional content or code. I get very low FPS on Xperia XA (Mali-T860 MP2).

As there are any other ways to make Unreal run faster on Android low-end devices? Same scene on Unity would give me 50 - 60 fps.