Optimizing game - Most important to reduce Texture resolution or Lightmaps resolution?

I have to optimize my game due to lag - what’s most important, reduce the texture resolution or the lightmaps resolution?

Resolution shouldn’t bottleneck performance unless you are running out of vram.

you might want to study: Performance and Profiling | Unreal Engine Documentation
its a great bit of resource everyone should read/learn from.

Thank you guys!