Slack is an amazing chat tool for teams, we use it daily at Automattic. Unfortunately it is unusable on slow connections, something I run into sometimes when traveling; recently in Nicaragua, rural Ohio, and Silver City, New Mexico. I wish it worked better in those situations.
To their credit, the loading messages are humorous and keep me from punching the wall because I’m smiling at the clever copywriting and positive attitude.
If you haven’t yet, try out Slack.