The restriction is not how many users but how much data. If it gets to big you will see this... hope this answers your question.
"Notes error: Field is too large (32k) or View's column & selection formulas are too large"
Last Wiki Answer Submitted: November 29, 2012 9:48 am by Gabe952710,615 pts.
If you live outside the United States, by submitting your email address you consent to having your personal data transferred to and processed in the United States.
You can check various limitations including your query in the link below:
http://publib.boulder.ibm.com/infocenter/domhelp/v8r0/index.jsp?topic=%2Fcom.ibm.notes85.help.doc%2Ffram_limits_of_notes_r.html