> Why it uses 400mb I have no idea.

Yes, this is an important detail as well.

Make a Slack clone, but have it perform way better than the original (less RAM, CPU usage), with a smaller storage footprint.

Also deliver on features faster than the original. And have those features be more tailored to what the users both want and need - and things they didn’t even know they needed as well.

This is, after all, what’s being promised, no?