A fast host could be argued to be a prerequisite in 2010, and a fast site too, if your web designer has any clue.

Does server speed has any influence on Google ranking?.

I’d imagine it is already part of the algorithm on some VERY minute level (why not?) and probably is going to be turned up a notch in 2010, but small differentials in page speed load will be clearly NOT as important as just about every other onsite seo factor and even more important external factors which encourages Google to rank your site higher.

If your server is dog*&^% and your website takes minutes to load it’s a bad user experience (why SEO have always advised don’t use crap free hosting) and your site probably doesn’t deserve to get high Google rankings even as it stands.

Here you are some tools to check your site performance:

1. Pingdom Page Load Test tool
2. Website Optimization Speed Test Tool
3. Uptrends Page Load Test Tool
4. Submit Plus Page Load Test
5. Link Vendor Page Load Test tool
6. Compare Yours & Competitors Page speed
7. Tools to speed up your site (defo worth a read)

… and you always have Page Speed by Google (extension for Firefox browser)