The following solved my slow loading times in 9d before the solution I use to wait up to 10-15 minutes now it's a few seconds.

Sony Creative Software - Forums - Vegas Pro - Video Messages
CineForm codec playback issues in Vegas Pro 9

Ken, MANY people who had the slow loading issue in 9d says they load quickly in 9e. However, there's been a couple of reports where some people have had slow loading in 9e - they're probably tied to some specific format of video but I don't know what formats may still be affected.