Sorry to hear about your experience with the Share for Review feature. There is no limit on the size or users for this feature. We’ve tested with a 100-page fairly complex document with multiple reviewers sending their comments back to InDesign. We have not experienced any slowdown/sluggishness in InDesign or the browser.
Do you see this behavior with a specific document? Do you see lag while working within InDesign or on the browser?
This information would help us assist you accordingly. Looking forward to your response.
I've asked my team for more specific examples and screenshots. We are seeing sluggishness and lag on both sides...InDesign and the browser. But I think the biggest concern is from the InDesign side. They can get 100s of comments on a document. SFR is our go-to review process. I will update this thread next week with their comments.