One of the major selling points for the Kindle Fire is its Amazon Silk Web browser — a cloud-accelerated browser that turbo boosts page load times with Amazon's supercomputers. Turns out the speed boosts aren't really much to boast about.
According to benchmarks testings by Sencha, the Kindle Fire's Amazon Silk browser has virtually "no to low impact from 'Accelerated Browsing." They conclude that the Fire "isn't designed to run HTML5 apps as a primary goal."
Sencha also learned that the Fire uses an older version of WebKit than the Xoom and PlayBook which could be the reason why it's not up to snuff in rendering HTML5 and CSS3 animations properly.
It seems to be that the best Web browsing experience is still on the iPad 2 and they even say the PlayBook comes in at a close second (I have to agree).
However, the one thing that the Fire has over the iPad is still Adobe Flash support (oh wait, that's dead).