Something which is going to be of increasing importance in 2010 (if it wasn’t important enough already) is the page load time of your website. Why? Two main reasons: visitors are becoming increasingly less patient, and Google’s heading in the same direction.
I think that far too much has been read into some comments from Google’s Matt Cutts that site speed is going to be part of Google’s ranking algorithm, but it’s an important factor regardless. If your site loads anything less than instantly on business broadband, see if it’s the server’s fault. It’s unlikely, but if so, there’s an easy remedy: move servers. If it’s the back-end system, you’ve got a much bigger problem, but it’s another reason to rebuild your website around a more modern, faster content management system.
There’s a really good look at the subject in Are Long Page Load Times Driving Your Visitors Away? on the ROI Revolution blog.