Webex wait times depend heavily on the number of attendees per session. In our experience, doing a few webinars per week, the more attendees the longer it takes to update into Marketo. This is a Webex issue, as they take much longer to compile all the attendee data. Since Webex reports on attention and log in/out time, it needs to process. 1200-1500 registrants sounds like it would take quite a while for Webex to process, as is the case in our largest webinars. Unfortunately that sounds about par for the course with Webex.