Hi,
I have seen that too sometimes in Desktop Safari - but this is not an krpano issue and have notthing to do with the filesizes or the internet connection - it's the Safari itself - it seems sometimes (maybe when it's running out of memory or so...) that the browser is trying to swap out or reload/rebuild it's internal images/textures,
but this is something that can't be controlled in any way, I would call it a bug/problem in Desktop Safari...
best regards,
Klaus