Apple pushed out Safari 5.0.1 on Thursday morning, which includes several bug fixes and enables Safari 5's new extension system by default. Like many geeks, we here at Ars had already enabled extensions via the the debug menu in 5.0, but we ran into numerous performance problems in the 5.0 release. Though there still appear to be a few quirks with some extensions, Apple has definitely addressed the performance issues with this latest update.

With Safari 5.0, loading new extensions sometimes caused performance to slow to a crawl, and often caused beachballs of doom if more than a handful of tabs were open. Disabling the recently installed extensions would eliminate the problem.

Thursday morning, however, I installed Safari 5.0.1 and began installing over a dozen extensions, specifically choosing several that I believed would tax performance if loaded in the 87 tabs I had opened. In addition to installing Twitter, MLB, and several other extensions featured in the newly launched Safari Extensions Gallery, I also enabled extensions that had caused performance problems previously.

With over a dozen extensions installed, including extensions that add toolbars, buttons, status bars, and contextual menu options, Safari kept chugging along without a single performance issue. In fact, only the MLB toolbar caused the fans to ramp up on my aging first-generation MacBook.

Now that the performance issues have been ironed out, however, Apple still needs to put some more work into improving the overall extension system. For instance, loading new extensions will add buttons and toolbars to the current window, but many will only work on newly opened windows. We have also heard reports that some won't work properly until restarting Safari. Repeatedly clicking buttons and toolbars and getting no response is a fairly maddening experience.

And unfortunately, the way the button icons work, your toolbar can quickly fill up with indistinguishable circles and rectangles. Developers have mentioned to Apple that they would like to do more with buttons, such as having color icons, so that may be addressed in a future update.

Still, Safari's extension system offers developers quite a bit of latitude in building additional functionality for Safari. Let us know what your favorite extensions are so far in the comments.

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