YSlow analysis of Ensembl home page after changes. Combined screenshots of YSlow in the Firebug window, showing the 'Performance' and 'Stats' displays respectively. On the left are the factors assessed by YSlow, with a score next to each; the overall score (B) and percentage (89%) are shown at the top of the column. On the right is a table of files downloaded for the page, with file sizes and HTTP request totals. In the optimized page, cached files no longer triggered HTTP requests, resulting in a single request for the HTML file itself.