No problems here, I refresh all 86 daily greyhound markets at 0.5 sec, from 15 sec before off and everything performs faultlessly. Ensure your data request rate is large enough to cover your system requirements, without exceeding Betfairs limit. Go through every item in Settings and ask yourself, do I really need these data refreshed as often, if at all. Also ensure that "Retrieve all price offers" is not ticked.