UDK performance Thread

What are some things I should consider when making a game/level for UDK to optimize performance drastically?
Would disabling lightmass be a great help? Turning off motion blur? What about using 512x512 textures in materials? Etc.

Lightmass is for static lighting, it doesn't affect in-game performance. Everything else is common sense. Less post-processing, lower resolution meshes and textures etc.

The only thing that really chokes out a system are shadow and particles effect. That's why shadow quality and effects quality such as smoke are common solution to increase frame rate and playability. Base on my experience with UDK or UE3 in general, dynamic shadows are the performance killer, the reason are they are not static so you can't pre bake the shadow, and the more moving object you have the more it will cost you for each dynamic lights.

Motion Blur is more of a client side option which mean you can add it in and let the user decide if they want it on. Textures sizes shouldn't be a problem for most cases.

Thanks I'll have to keep that in mind
And a bit off subject, but you guys wouldn't happen to have a lava material tutorial or anything like that, would you?

Edited by: Aimforthehead

Don't forget collision. Having some complex collision can slow a system down. It's constantly calculating collision vs. collision events every frame which can become quite laggy.