You can also try this fix, as it is simpler and won't mess anything else up before you mess with the terrain system; it's boosted many players FPS by around 30 on average for very minor tweaks

"- Turn off v-sync, it is bugged and causes problems

- Steam launch options for Valheim to force fullscreen nets some good FPS returns;
''-window-mode exclusive -screen-fullscreen''

-Find your Valheim directory, find Valheim_Data, then open the 'boot' file with notepad. copy and paste these lines of code to the very first line of this file;

gfx-enable-gfx-jobs=1
gfx-enable-native-gfx-jobs=1"