Comment by Analemma_

"It's slow because it's Electron" is a lousy excuse: Discord is an Electron app with more or less the same purpose and it's perfectly snappy. Hell, Microsoft's own VSCode is considered the gold standard of how to do Electron apps well. It's fast as shit, assuming you're not opening huge files. It baffles me that the Teams org isn't begging the VSCode org for some of their performance mojo.