Source Built Unreal Engine Interface is absurdely slow

Hello guys,

I’m currently working on a project that requires a custom built Unreal from source code v4.13.
The changes made to the original source are minimal and only provide VR Fullscreen Output.

Now here’s the problem. The engine interface itself is working just fine, drag&drop actions, opening assets etc.
But each and every dropdown, menu, text, checkbox etc. is absurdely laggy.
I’m talking about easily 5-20 seconds waiting time until a dropdown opens after rightclick or opening another menu branch.

I’m aware that you probably don’t/can’t support custom built engine versions. But I just need a pointer in the right direction. Is there something specific in the source I could check? Anything helps.

I tried rebuilding the version several times with no effect.

I also noticed 2 things:

  1. The lag/duration of stuff not appearing is reduced when I move my cursor around a lot (could be my imagination but I’m pretty sure)
  2. If I restart the engine it seems to work better for a few minutes.

Thanks in advance for every help!

Best regards,

Max