Apple's Safari web browser is generally quite good: lean, fast, very good CSS support, simple interface. But it has one very nagging problem: when in HTTPS mode, it slows to a crawl. Maybe people with newer machines than my G4/400 don't notice it so much. But it's very noticeable on mine.
Checking out a couple of our own sites in Safari, which most of us here in the office use daily, I decided to open up a page in the Mac OS X port of Mozilla Firebird. The same page loaded much much much faster in Firebird. So then I decided to try OmniWeb 4.5, a native Mac OS X browser that now uses the same HTML core as Safari. Much Faster, Again!.
While OmniWeb now uses the Safari WebKit core, it still uses other OmniGroup frameworks, including extra networking libraries. So it's not terribly surprising that it could be faster, even with the same HTML kit. But it is annoying.
(OmniWeb also prints better than Safari, which has decided to print ENORMOUS text starting with version 1.1)
This makes OmniWeb and Firebird interesting products. They both take an open source rendering engine and in many places outdo the browser that is supposed to be that engine's champion.