I would love to hear what Lars has to say about this, but here is my experience:
A lot of textures with normal maps etc. do not slow things down in both my set-ups (Apple M1 and Intel i9 with a big ass graphics card). As this adds to a high quality look I tend to keep these in.
More beams (and multi lenses fixtures) do.

I make a live view filter that hides everything I do not need for programming.

What I sometimes do is reduce quality in the live view and record the dmx in a snapshot. I will make a rendered movie or still in the night in full quality.

It's impossible to comment on performance with so little information. It comes down to exactly what is in the project file.

Using more memory generally makes visualisation slower though, whether it's video memory or not.

The best way of optimising a project file is to start deleting things in order to discover what the bottleneck is!

Using more memory generally makes visualisation slower though, whether it's video memory or not. 

so what's the point of video memory at all?

https://www.quora.com/Wha...dicated-video-memory

Simple test.

Swidish hous mafia style 300 beam fixtures and one geometry box.

FPS 25 Quality 29%

Smoke delited fps 50 quality 100%

That doesn't seem right. I get 60 fps @ 100% with 300 MMX Spots on an RTX 2070.

Can you screenshot Capture's about dialog?