The opening of the game, and optimization is just the way the game is. Since launch through to Patch 8, it has not run smoothly for anybody that I am aware of.
Cutscenes seem to have a framecap, and may stutter.
The main menu may have some "traversal stutter" as it switches from the optimization, but it should not continue to stutter.
Given you are having trouble when sitting at the main menu, viewing the Jedi Temple on Coruscant, I would suspect the RAM.
I have an 8-Core / 16 Thread, Zen 3, Ryzen 7 5800H (3.2GHz Base clock / 4.4GHz Boost), with 32GB of DDR4-3200, and an RX 6600M (8GB) GPU on a PCI-Express 3.0 x8 bus. I don't experience stuttering at the main menu.
My 8-Core CPU is not fully utilized, but it does frequently use 6-Cores, and occasionally drops to only 4-Cores. So it is not likely to be a significant deviation from your configuration. Given that the game was released for the PlayStation 5, where the RAM configuration is more direct and not so constrained by a 2600MHz bus, I would not be surprised if RAM was a source of performance problems on PC.
I have not tested a 16GB 2600MHz RAM configuration for comparison, so I cannot be certain either. I have seen the game use 24GB of RAM on my configuration.
Another suggestion might be to make sure that you have closed all background programs, run the game full screen, and do not Alt-Tab or use multiple monitors. Windows may reduce the available VRAM if it registers conditions where you might switch to a different application. Performance monitors and/or screen capture applications may introduce unexpected lag on weaker systems.
Some users have reported issues with USB devices like storage drives, or even interference on the wireless spectrum with regards to a Bluetooth controller.