It's unclear what you mean by "page load time."
>> If you mean, how long, from the time your server receives a POST, GET, HEAD, etc. request from a visitor, to the time your server has parsed its response stream and sent a response header back to the client, then you can monitor that several ways:
1. If you are using Apache, you can use ab to benchmark your server's performance:
http://httpd.apache.org/docs/2.0/programs/ab.html
There's also a metrics API you can download as an Apache package:
http://hadoop.apache.org/core/docs/r0.17.2/api/org/apache/hadoop/metrics/package-summary.html
2. If you are using PHP, you can easily determine the time of a script's execution using this method:
http://www.webdesign.org/web/web-programming/php/script-execution-time.8722.html
3. If you want to track how long it take to run an ASP.NET page, you can use the Trace class:
http://msdn.microsoft.com/en-us/library/y13fw6we(VS.71).aspx
>> If you define "load time" as the period of time between when a Web browser sends a request header to your server and the page has completed loading on that client's computer, you can do that with jQuery, using a simple AJAX script like this:
If you are looking for a more integrated management solution, you can try one of these open-source solutions:
http://www.opensourcetesting.org/performance.php
Otherwise, you can search for "Web server benchmarking" (since that is what you describe) and find all sorts of suggestions and services.