I tend to agree. Mozilla's constant tinkering with new features at the expense of performance has really hurt Firefox, at least on the Mac. On Mac, Firefox is also a poor port, lacking support for many OS X services. It doesn't even use the system print dialog. It uses more RAM and runs my fans up more than Chrome and definitely more than Safari.
Mozilla seems to have lost it's vision. Back in the day, they wanted to free the web from the chokehold Microsoft had on it. Early Firefox was faster, leaner, and supporting bleeding edge technologies. They actually innovated and arguably made a huge contribution to making the web what it is today. But now it's all about Google and rather than trying to beat them, they are trying to emulate them in many cases. Dumbing down the UI, adopting multiprocessing, and now Googles' extension model.
By this time next year, people will be saying "Firefox? Oh yeah... I remember them." They will go the way of Quatro Pro, WordPerfect, and VHS tapes.