Some parts of a web server I am administrating was showing a bad “felt” performance. Using Firebug, I narrowed down the problem : there were random delays in the delivery of the pages. Sometimes it was PHP scripts, sometimes CSS or Javascript files. Since CSS and JS files are static, it excluded a problem with PHP or the database. The load on the server was OK, so it wasn’t that either.
I finally found out that by disabling the Keep Alive feature on the server side, the problem disappeared. I still have to investigate what the exact problem is (Keep Alive is part of the HTTP standard and used widely). It could be a problem with the Content-Length that is not reported correctly by the server, causing the browser to wait for more data.
Filed under: Web, apache, delay, firefox, page access, performance