The first thing I looked for was a comparison with the official Slack client in terms of performance, since that's the only reason why I'd consider using this. Numbers for CPU load, memory use, time to perform certain actions, crashes. Doesn't seem to be anything available on the site regarding this, which is a shame.
I've literally never had or heard of Slack crashing, across Windows, Ubuntu and macOS, regardless of memory available (8-32GB) and use. Do people really have Slack regularly crash on them or is that just something that gets attached to Electron (for some reason).