I agree with using profiler to trace application performance.
Another things to note is that there are many possible reasons why the page loads very slow especially on initial load and these includes (1) grabbing huge data from database (you should limit the amount of data to be returned in your query or use sql paging for more effecient way. If your queries are slow, make sure you have proper indexes on them) , (2) displaying large images, (3) bunch of JavaScripts, CSS, (4) network connection, and so on... One way to see how long some of these things are taking would be to use the Chrome Developer tools, FireBug(firefox) or IE Developer Tools. They are available within your browser by clicking (F12), from there, you can monitor the Network tab which will indicate how long each of the individual processes within your page is taking to finish.
You should read about
speeding up the performance of your application. There a bunch of them out there. Just find them at google ;)
Once you are able to determine which part in your application or code causes the your page load slow, then you should rethink your approach in order to fix that.