in my testing, I didn’t notice any page load times that I would consider noticeably speedier. When speaking to Amazon reps, they made it sound like lots of people would need to hammer on Silk to start to generate usage patterns. Still, I expected to see some bump in load times, and I can’t say there was anything visibly different in the experience. In fact, the iPad 2 and Galaxy Tab 10.1 had much faster load times on most sites I tested side-by-side

Kindle Fire review on Verge

The whole Silk thing is brilliant. They had a slow browser all along, but they were able to get everyone, including the US congress, talking about how fast it is.