I think there is a combination of ‘factors’ here. iSpot is notoriously slow to load (since the recode?) and commonly, the pictures still may refuse to show, even after a wait. (some much slower than others) Watch the time it takes to load in the Thumbs in any post with more than 5 pictures. Admin promised (well, thought up) a hardware Update (three weeks ago)
Many of our (MY) pictures are quite big, some beyond 7Mb - that MUST be a factor.
And processing speeds at your own terminal, not to mention upload speeds from the web and transfer speeds from your router via the attic repeater. And then there is peak pressure on the Web itself.
There are times when I have to refresh twice but we should NOT have to clear our browser.
So, yes, compared to a lot of Websites, iSpot is not up to much at any time of the day.
This thread maybe ought to be here Photo size restriction?