I run Tower on my work computer which is an i9, 1080 ti with 64GB of RAM. My RAM is large because I need it to run the unreal editor without worry (editor content is not compressed like it is when we ship it).
Tower itself rarely gets above 8GB of RAM, unless there’s a lot of active workshop models, but it dips down as players change out.
I get 90-150FPS in the Plaza, over 100-200 FPS in condos, 150-200 FPS in game worlds, and 60-80 FPS in a very full condo. I don’t overclock anything.
My settings are all on Ultra, with AO and when I feel like having a better image I use 150% resolution scale. I’ve run it in 4K as well without issue.
My other metric for testing is my laptop, that has a 1060 and an i5. It runs Tower fine in Ultra settings as well with lower FPS. Around 80-90 FPS in Plaza, 100 FPS in game worlds, etc. I tend to set a frame limit of 60 FPS, though.
My worst case other metric for testing is a handheld, GPD Win 2. It runs Tower at like 40-50 FPS on all low.
I would highly suggest updating your graphics drivers, remove ALL command line startup options (many posted do not help with performance or even apply to our game), and look into your overclock settings (do you have enough PSU power?). Overclocking could be what is causing your issues.