Programming Sharepoint 2010 enables you to use a little helpful build in tool called the developer dashboard.
The Developer Dashboard allows developers to get some insight into what a page loads and how long times this takes. So if you have built perhaps some webparts for a page and this page suddenly starts to take a long time to load you could use the developer dashboard to check out which webpart is causing the problem.
Sadly the developer dashboard isn’t something you just turn on and off. There are 3 ways of enabling the developer dashboard (via Code, Powershell og STSADM). I found that STSADM was the easiest way, and the commands are:
To turn on the dashboard:
stsadm -o setproperty -pn developer-dashboard -pv on
To turn off the dashboard:
stsadm -o setproperty -pn developer-dashboard -pv off
When enabling the Developer Dashboard these information are shown at the bottom of every page