While it's fair to say Valheim isn't a bad performing game, not by a long shot, some players will be struggling to maintain that 60 fps sweet spot on mid to low-end hardware. Thankfully, one clever user known as RustyB3ans on the Valheim subreddit has found a nice, simple tweak that can boost performance by a good 20 to 30 fps, depending on your config. 

It's tough for me to see a huge difference, as I am running on a 3900X with an RTX 3080, but with this tweak, I have to say that performance did jump for me by about 20 fps on average. That's pretty good, frankly, and you may see better results on lower-end hardware. According to RustyB3ans, who has written a simple 3 step guide. It involves modifying the game's boot config file, editing it with notepad, and making a few changes to the config settings;

1. Find "Valheim" in your Steam Library, right-click it, click "manage" and then click "Browse local files"
2. Then go to the"Valheim_Data" folder
3. Find a file named "boot.config" then right-click, select "open with" and choose "notepad"
4. Then, at the very top of the file, add the line "gfx-enable-gfx-jobs=1" 
5. Then below that line, also add "gfx-enable-native-gfx-jobs=1" 
6. Save the file, then go back to your Valheim properties window in Steam
7. Go to the "launch options" field and enter "-windows-mode exclusive" 
8. Open your Task Manager by using CRTL + ALT + DEL or right-clicking the start button
9. Go to the "Go to details" tab
10. Find "valheim.exe" and right-click it, then choose "set priority" and change it to "high"

Once these steps are complete, you'll see a huge boost in performance, although unfortunately, you'll need to perform that last step every time you launch the game.

I can confirm this does work, but your mileage may vary and it is obviously at your own risk, if you break it, that's on you. But RustyB3ans tweak does seem to work for most players, although some do see weird lighting or graphical glitches - in this case, they suggest removing the "gfx-enable-native-gfx-jobs=1" line from the boot.config file.

Does this work for you? If so, what boosts do you get? let us know down in the comments!