Lately Safari has been prone to freezing (pinwheel of doom scenario) and other undesirable behavior when browsing Flash-intensive websites. The problem seems to occur when viewing videos on Youtube or other websites. Stopping one video mid-load and then starting to view another video will often cause Flash to go belly-up. Sometimes when this happens the <div> where the Flash video should have been appears empty. The problem is usually corrected by restarting Safari.
FYI, I'm running the 64-bit version of Snow Leopard on a 2.4 GHz Intel Core 2 Duo MacBook Pro with 4 GB of RAM and in general I'm very satisfied with its performance.
Could this problem be related to Apple's decision not to allow Adobe to develop an implementation of Flash for Apple's hand-held consumer devices, such as the iPhone? Steve Jobs stated that Flash is a closed platform not suitable for open application development. He also stated that problems related to running Flash is the number one reason macs crash. It's kind of strange that I'm noticing such problems a lot more now that Jobs has made that statement, but then again it could just be my imagination.
In Adobe's defense, CEO Shantanu Narayen states that Flash is not a closed platform and that Flash does not cause macs to crash, rather those problems are related to underlying issues with the Mac OS X.
While many geeks feel that Flash should be phased out entirely in favor of the up-and-coming HTML5 video format, I personally feel that Flash still has a place when it comes to ease-of-development for interactive web content. At least for a while until HTML 5 has time to mature and gain wider acceptance. This video from Google's annual web developer conference demonstrating HTML5 in action is pretty slick:
