Which sites are you loading in the tabs? These days Safari actually shows that rainbow spinner when the background process that runs the tab is hanging, even t

Which sites are you loading in the tabs? These days Safari actually shows that rainbow spinner when the background process that runs the tab is hanging, even though Safari.app itself is perfectly responsive. This usually is indicative of a problem with a site loaded in one of the tabs in the window (I believe Safari does process separation per-window), as opposed to a problem with Safari or WebKit itself.