The following table is a simple to use comparison of how fast WordPress runs at a number of hosts. The comparison is based on up to a year worth of gathered data. The "Best WordPress hosting" title here is given to the company where the WordPress application was fastest. 

The Best WordPress Hosting performance Rank Hosting company Ranking average #1 HostGator 394.19ms #2 1and1 460.36ms #3 Justhost 779.52ms #4 Lunarpages 915.52ms #5 Dreamhost 970.5ms #6 Ipage 1240ms #7 IXwebhosting 1400ms #8 Hostpapa 1550ms #9 HostMonster 1610ms #10 Netfirms 1730ms #11 Fatcow 2203ms #12 Godaddy 2400ms

You should also take into account the host's uptime and other data that you can find on our site. Obviously, you wouldn't want a fast blog that is down 20% of the time. No one would. 

Keep in mind that this comparison is done with an empty install of WordPress. A real life blog will have a bigger database, containing all the posts that accumulate over time, which will slow things down. On the other hand, the monitored WordPress script here, does not employ any kind of caching. There are caching plugins out there that will improve a blog's performance, possibly quite a bit. The slower the host, the higher the impact of caching is likely to be.

In any case, the figures you see here are probably not perfectly reproduced in a real-life setting (but they will be proportional, so the ranking stands), or on all servers a host may have. 

Good luck!