How to test performance of website parts?

I've actually obtained a job to test a website that is somehow struggling with its performance. In Detail I should pick out different parts of the document and check out their waiting->load->finished states. Since I'm familiar with firebug i've tested many sites as a whole. But now i need to know when starts a special DIV rendering, when is it finished and how long did it 开发者_StackOverflowwait before. The goal is to find out wich part of the website took how long until painted.

I doubt you'll be able to measure individual parts of a page they way you want. I would approach this by removing parts of the page, measuring the subsetted page, and inferring from those measurements which parts are slowest.

Keep in mind that this sort of logic may not be be correct. For example, you may have a page with two parts. You may measure the two parts independently by creating subsetted pages. The times of the two parts added together will not equal the time for the total. And one part seeming slower than the other doesn't mean that when combined, the "slow" part is responsible for the bulk of the time. Browsers are very complicated machines, and they don't always operate the way you imagine.

AFAIK, speed of printing a div is not something you should worry about. If there is some sererside language, then i would suggest assiging a variable to current time before a portion starts and compare it to the time right after the portion ends. You can subtract them to get the time it took do work that portion out.

If there is javascript involved, then i would suggest chrome dev tool's timeline panel. It shows everything, from css recalculation and printing of the style/div to ajax/(if using) db queries..

As you are familiar with Firebug you can use HttpWatch tool for recording the exact request and response time of all specific http requests made by your browser.

so when a special DIV rendering starts this tool will capture the request and response time for the same.

http://www.httpwatch.com/

All the best!