There is almost universal hatred of the Slack app in our client relations department, due to performace. All use Mac laptops or Windows desktops, none of them know the term "Electron".
I wonder why people run slack stand-alone. I run it as a pinned tab in my browser and with browser notifications it works great. Very few issues running it this way and performance seems good.
I have Chrome users for browsing, personal email, work email and Slack. I had Slack in a separate Chrome window, in a pinned tab. I noticed that changing to my communications space was slow. By eliminating windows one-by-one, I discovered, the culprit was the Slack pinned tab. I tried the Slack standalone app instead, and that slowness is gone. I can't explain why, but the standalone native app may actually perform better. I think it's worth checking out.
I've gone back and forth between in-browser and stand-alone, but as my number of Slack teams grows, browser tabs get considerably less appealing. (I have five I monitor regularly and four more I don't care much about.)
