how to diagnose web page half-loading problem?

Often on my site when I open a page it loads half-way (as in the PNG above) and then just stays there loading forever - if I do a page refresh it then properly loads the page. I need some leads how to diagnose this issue.

The load on the site is not heavy at a开发者_如何学运维ll, and SQL logs also do not show any load.

Any help appreciated.

Update : thanks all for the comments - there are no js errors (except the usual adsense issues, i tried without adsense, same problem) - i've run with chrome dev tools - the loading of the page just stops after a few seconds and chrome loads forever and ever. see :

I really feel this probably is more of a server-side issue ?

Do you have some embedded javascript on the page that is hosted on another website? That can stop the loading if it's waiting for something external.

I recommend using Google chrome or Firefox's Firebug. Both of these include tools that show loading times and may point you in the direction of what is taking too long, what didn't load, etc.

• Google Chrome: right click on page, inspect element, "timeline" button.
• Firefox's Firebug: right click, inspect element, the net tab.

What browser are you using? If you are using Google Chrome or Safari, there are some excellent debugging tools available out of the box with both of these browsers. If you use FireFox, FireBug is an excellent debugging add-on you can use to debug as well. I believe IE may even have debugging tools as well, though if not, I have heard that DebugBar is a decent tool to use. It's been while for web dev for me, so I'm a little out of the loop as far as IE debugging tools go.

Load any png or jpg files separately and see if there is a snag on image load.