It's not that fast yet. If you want to refresh more often, I recommend querying differently than you are. Filtering by territory is relatively slow and if you are grabbing from all territories anyway, you might as well filter on your end.
How can I reliably tell where’s the line?
If you run a query and it consistently takes more than ~100ms (your queries when compounded on each other were taking ~15000ms on average), you are doing something that's high load and ideally:
you should rate limit yourself
let me know so I can make it faster on our end and advise on how to make it faster on your end
It's not that fast yet. If you want to refresh more often, I recommend querying differently than you are. Filtering by territory is relatively slow and if you are grabbing from all territories anyway, you might as well filter on your end.
If you run a query and it consistently takes more than ~100ms (your queries when compounded on each other were taking ~15000ms on average), you are doing something that's high load and ideally: