Blood Splatter FX - Huge Performance Drops

[Eulixe]

Firstly, thanks for what you guys do. The time and effort are majorly appreciated.

I have searched through the Bug Tracker and can't seem to find this duplicated but maybe I've missed it.

Whenever I am close enough to a particle fx my performance seems to tank. This is especially noticeable when fighting in melee combat and a couple of the large blood splatter fx's trigger one after the other. I can go from a stable 60fps down to singe digits. using faster weapons such as daggers can bring the game to a crawl.

As soon as these effects have disappeared the frame-rate returns to normal.

Attached screenshot shows this. Massive GPU Spike (running a 970) and what looks like a huge dip in physics (I'm not sure what that top white line represents)

Anyone encountered a similar issue?

As an aside - This happens on a 100% unmodded version and does not happen in the original engine.

https://ibb.co/8jXMr7W

[AnyOldName3]

There are a few things that can make particles slow:

• There's quite a lot of overdraw, where multiple things are written to the same pixel, as lots of translucent particles overlap each other. GPUs don't like this as it's more work. There's not really anything that can be done about this, but anything that makes each particle faster to draw will make it less apparent.
• We have lots of particle processing on the CPU, which doesn't itself take that long, but does mean particle data needs uploading to the GPU each frame. GPUs don't like that. I don't think this is what's happening here, as it's most likely to show up as Draw rather than GPU, but it's possible your driver is reporting it weirdly. We're hoping to eventually move particle processing to compute shaders on systems that support them, which should eliminate the problem, but we need to finish removing bugs from our CPU implementation first.
• There have been some recent changes to make particles work more similarly to how they did in the original engine if you're using a nightly, and so things are kind of in flux at the moment. It's better to optimise things once you know they're doing what they're supposed to so you don't end up wasting effort.

[Eulixe]

Hey, thank you AnyOldName3.

The problem can be mitigated by staying a decent distance away from the fx, it seems the closer the camera is too them, the worse the issue is. This would make sense with what you're saying as there would be a larger ratio of pixels on the screen being overwritten.

I'll have a mess around with drivers and see if there is any improvement.

Are you aware if you encounter the same issue on your own rig? This would go a ways to determine if this is being caused by GPU drivers or if it's engine specific.

[akortunov]

https://gitlab.com/OpenMW/openmw/-/issues/4912