Hello Mike,
Thanks for reaching out to us. I’m sorry to hear about this issue.
A lot of attendees indeed can have an impact on the load speed of the event page on the front-end and the attendees page. That is likely to happen with 1000+ attendees.
This is a performance related issue we know about and we have a bugticket for it, so our developers will take a look at this. Unfortunately at this time I cannot give you any set date when this will be fixed.
For the front-end a caching plugin might help or not showing the attendee list. You can find that setting when you edit an event and you click on the Settings button in the tickets box (screenshot).
I am going to set the status of this ticket to “pending fix” and we will update it once the fix is released.
If you have any new questions or issues please create a new ticket and we’ll help you out.
Thanks and cheers,
Andras