How slow are the rest of your tools? The Slack client probably performs worse today than it did a few years ago. It has the laggiest interface of any of my tools, you can watch your CPU spike to 60-80% just switching channels. Just do it right now, open up htop/top/atop/Activity Monitor - whatever you want, and just switch channels. Laugh as the Slack client wastes a universe's worth of time just... rendering a DOM with plain text. It is genuinely pathetic how bad the client is.