I recently moved to a new VPS server for my site and have seen a vast improvement with the speed of the site. However, my Analytics have dropped to around one fifth of what they were before. The site has gone from getting around 700 visitors per day to 125. Does anyone know what might be causing this?

From looking at the Analytics the site is still getting traffic from different parts of the world as well as a variety of referrals, search hits, etc., so I can't see that there's one particular area that the site is suffering in. Plus, a lot of the pages are still ranked really high in Google.

Can anyone tell me what could be causing this? Could it be a caching issue? Is there anything different I need to do after moving to a VPS server?