A family of Microsoft spreadsheet software with tools for analyzing, charting, and communicating data.
Hi GEHenson,
To answer your questions:
1.Is there a hard limit?
No, there is no hard limit. If all the users are using Excel Online, they can all edit the file without locking each other out. Check this: Allow multiple users to edit simultaneously in Excel Online (coauth co-auth).
2.After how many would a team start seeing slow-downs on it?
In fact, there is no accurate number about it. The best practice should be less than 30 people when co-authoring in Excel Online. A similar thread is for your reference:
Thanks,
Sky Pei