We recommend hosting sessions of 100 users (or less).
This is not hard-coded, you can have 101, 102, etc. However, as more users join in the session, in general overall performance will degrade over 100 users.
If you are going to host a large session (close to the 100 user limit), we recommend only one person (the presenter) share their webcam. If possible, upload the presentation as PDF and share the slides (as opposed to using screen sharing).
Overall, for best performance, we recommend 100 users or less.