How did you come to the conclusion your site was slow? Visitor complaints? By the way, recently in the AdWords Blog, Google said something which indicates it is finally understanding the significance of slow servers to its profits. I have never seen anything from Adsense about making sure pages load fast enough. Google says it's going to punish advertisers whose landing pages are too slow. But what about publishers? How much money is Google losing by poor servers? Millions? How fast is fast? Are shorter pages the equivalent of a faster server? How much faster are your new servers? I hate to bother with server changes if it's not going to help. But the 25% income boost is intriguing. How do you know you couldn't make another 25% with even faster servers? What are the internet industry standard server performance tests?
i think its more like having a faster ISP connection than the faster server itself. any server should be faster than your ISP connection. if it is not, then you are dealing with wrong host