4.26.2 Bug / FPS drops over 50% / DX11 and DX12


apparently some have already noticed the bug 4.26.2 with the FPS drops to over 50%.

I searched forever what it is and had found that it is due to RHI DX11 / DX12.

My game had an average of 120FPS, now at version 4.26 only 30 to 50FPS.

With an empty project the FPS collapse, now set Windows DX12 the FPS go up. If you set DX11, the FPS drop.

Now you have the problem that this also affects shipping and players with old systems the game crashes after some time.

Switching to DX12 only helps until you quit your editor. If you now start your editor, the FPS collapses even with DX12. If you click on DX11 and then on DX12 again, everything is fine again. But if you now pack your game with DX12, you have microstutters in the game.

Is there any news in this regard yet?

I noticed something else, with the 25 version everything was Ok. Even if you changed DX11 and DX12. But if you switch to visual studio 19, the problems with the FPS start. If you do 17 it is ok, if you do DX11 and 17 it is also ok. If you do DX11 and visual studio 19, the FPS drops immediately.

I think that this problem is already for a long time.

Tested with an empty project and on 3 systems.

We’re using both DX11 and DX12 from the 4.26 branch and not noticing any such problems. Performance slightly increases with every engine update.


Here would be the 4.26.2

It’s nothing in the world and FPS go down. Jumps up every now and then, and in shipping the FPS are just as bad.

With the 25 version everything is ok in shipping.

Also a friend of mine has the same problem.

Here would be another similar problem, FPS problems.

I have a weak PC and the same problem with large FPS drops (in time periods). It appears in the UE 4.26.1 and 4.26.2 versions. Everything runs smoothly and suddenly unexplained drops. My application only consists of a sphere that rotates around its axis. No FPS drops should happen.

I’ve installed the UE 4.25.4 version and the large FPS drops still appear (from time to time). What is wrong? How to fix it?

What I currently got out of it is that it collapses at DX11 FPS. At DX12 it occasionally twitches down to 70fps and up again.

Same problem occurs on other computers and also with friends.

The main problem is that it is transferred to the shipping.