I use quite a few electron apps and none of them seem to get that bad except maybe atom but I have a TON of open windows.
Slack gets pretty resource-intensive when the user is part of multiple workspaces. I know one of my co-workers is part of three or four, whereas I'm only part of the main company workspace. Co-worker's Slack memory usage is around triple that of my own.
[1] https://electronjs.org/