Hi Mark,
Seems like you’re GPU bound, but there’s also a sudden increase in CPU usage. I recommend, you use the stat gpu console command to get the real-time GPU profiler and look for the highest timings.
Since you mentioned a memory warning, I also suggest you take a look at those commands: stat rhi, stat rendertargetpool and stat texturegroup.
Here’s an article about GPU profiling from the documentation: GPU Profiling | Unreal Engine Documentation . It might also be worth taking a look at profiling.
Do you mind sharing your rig specs? And here’s another question, just because it solved the last issue someone else had, are you using ray tracing?
If your screen get’s cluttered with stat windows, just use stat none, it should disable all currently active stat windows.