From a system wide point of view..think about these in no particular order they can ALL impact

• Start with read writes from HDU, (NOTE if it moves it breaks) SSD arent moving HDUs Are potential bottlenecks
  
• How many pixels or datapoints in the image area is the GPU trying to render. so get a some reference data and even compare to freely available refernces of similar same GPU's
  
• Whats your CPU ALSO doing Stop or pause unnecessary background tasks (Windows update trying to get you to windows 11 for example!!
  
• As mentioned by @FissionChips Which Benchmark are you using... and is it the problem? just saying
  
• have you tried lowering the display resolution and seeing what performance is like? in Audio there is a setting known as "Parity/Unity" setting EVERYTHING to Parity gives The best performance and then you adjust a little bit here and there for the room the instrument and the mix to the audience..
  
  (what does this mean?).. Just because you have a Lamborghini doesnt mean you drive with the pedal to the metal all the time!
  
• Please tell me its not a Laptop if it is you MUST set up dedicated Graphics to run on Valheim.exe
  
• Modded or Vanilla
  
• Solo or MultiP
  
• And its not when the Save game lagg happens by any chance?

Sorry some questions appear dumb but its all checkable :-)