Sudden ~10% drop in performance after 10-20seconds

Hey Epic,
I noticed while eating my sandwich today that in the editor I get sudden drops in performance if I let it run for 10-20 seconds. If I drag one of the editor windows that forces UE4 to stop rendering (Project Settings, GPU Visualizer, Scene Outlier, Levels, Message Log, etc.) for about 10 seconds and release - the performance is reset back to peak levels.

In summary: I start up the editor and everything is running at 100fps. I let it sit for 10+ seconds and at some point it suddenly drops to 90fps. I drag an editor window around for 10 seconds and release - and it goes back up to 100fps. If I let it sit for 10+ seconds at some point it suddenly drops to 90fps. If I drag an editor window…you get the idea.

I’ve repro’d this in multiple projects, on multiple machines, and even got someone in the chat channel to repro it. I’ve also repro’d this in cooked version of our game (by dragging the windowed version of the game around for 10 seconds).

Thanks!
-Chris

Hey, Chris!

I’m trying to repro the bug here at the office. Can you tell me what version of the engine you’re on and pass along your dxdiag? That would make it much easier for us to get a consistent repro.

Thanks!

Hey Jonathan!
Sorry about leaving that out. I’m using UE 4.3 (vanilla release build) - Windows 7 - an Nvidia Titan Black with drivers 9.18.13.3788 released 5/19/2014. The machine has been out of the box for a week so you can expect not much has been done to it.

Let me know if you need any other information. Thanks for checking it out.

-Chris

I did a bit of research here at the office, and it looks like this isn’t happening in our internal build, but I was able to reproduce it in 4.3. I’m not sure what’s causing it - maybe something related to the way the objects in the level are loaded in?
Anyway, that means that the bug should be fixed by the next big release.

Regards,

Jonathan

Perfect! I love mysteriously fixed bugs.