My discord was lagging increasingly during long calls on my Manjaro installation. I searched a bit on the Wiki but the fix shared there didn't work for. What worked for me is this answer on the Discord support forum, that I will detail a bit here. Start by moving to the right folder:
npm package of your distribution.
yay -S npm will do. Once this is done, unpack the
core.asar file with
npx asar extract core.asar core