I think this is probably the same behaviour as the previous version of SourceTree, I just happen to be using 1.5 beta 1.
Sometimes I'm working in my git working copy (and I usually have a couple git working copy windows open), and just browsing around, doing whatever, and SourceTree will refresh the commit log like once every few seconds. It'll refresh in all open windows, too, not just the one I'm actively using. I'm just seeing that spinner going on, and going off, going on, and going off, sometimes 5-6 times. I can't figure out what's triggering it.
For it to refresh once between major actions (e.g., committing, switching branches, applying a stash), I can understand. But 3-4 times? Any idea why it's so frequent? It's kind of distracting and seems unnecessary. It seems to me that SourceTree could be streamlining its git operations into one chunk - issuing one apparent refresh, from my point of view - instead of having it broken up into many refreshes.
Plus it doesn't need to refresh the windows that aren't active, just the one I'm actively working in. But it will do refreshes everywhere. It feels like a waste of CPU time and it's pretty darn distracting from my workflow.
I have that checkbox "refresh when files change" turned on in Preferences, which I think I want to keep on. I'm not even changing files for these refreshes to happen so often. There's also that "check remotes for updates every 10 minutes" setting, which seems like a good idea to me - but I'm hoping that if nothing has changed since the last check of the remotes, I don't have to see that spinner. It should just silently refresh in the background if nothing's changed, in my opinion. Same goes for the "refresh when files change" setting - don't show me the spinner if nothing's changed.
Maybe I'm asking too much. I just find this behaviour to be more distracting than it is in GitHub for Mac, which I think just does its refreshes once when the app regains focus, or you switch views or something.