I left it running when I first wrote the comment. Went back to it just now, after nearly two hours, and the memory usage didn't increase. Still at 120-130 MB.

I left it running when I first wrote the comment. Went back to it just now, after nearly two hours, and the memory usage didn't increase. Still at 120-130 MB. My guess is that compared to Slack, Github app doesn't really do much when idle. Slack fetches user statuses, new messages, notifications and so on. When you have an open channel with ongoing conversations that will add up in the RAM. This app doesn't seem to do anything when idle, so the RAM usage doesn't increase.