Slow loading page

I have a client, that has an issue with a few pages that load VERY slow. (20 to 30 seconds maybe)

checking microtime() at the begining and end of the page load only shows the elapsed microseconds to be 0.14907288551331 seconds.

This leads me to believe that I should be looking more to the .js libraries being loaded, a jquery codes. Does this sound logical?

I'd suspect network latency first.

It happens on specific pages only.

Does it happen on all pages and only pages using .js libraries?

A good way to figure out whats going on is to use some sort fo browser based developer tool (Firebug, Chrome|Safari Developer Tools). You can see if there is something, like js library that is loading slowly. If you suspect its js loading you can also try and move all of your js libraries to the end of your page and see if that makes a difference or look into a js library that loads in your js last. This is a screen shot from chromes:

https://www.evernote.com/shard/s194...cd9eb2631a6642f

Also take a look at Yahoo's YSlow project. I think it comes bundled with firebug.

Thanks for your help folks. I was wrong on this after all.

I'd forgotten that when you view source with firefox it reloads the page instead of pulling it from memory. This means the timer figures I was looking at, were not from the original page view, and where mySQL was using cached values, therefore going a lot quicker.

Saw this presentation of Chris Coyier's the other day. It sounds like you have your issue solved, but this is still a good watch for anyone reading this thread who wants to know some simple ways to improve their load time.

http://css-tricks.com/video-screenc...ebsites-faster/

That's a great vcast. Here's a list things you can check out I compiled from my local PHP meetup group:

Tools to Help Debug:
* Firebug[1]/Yslow [2], Google PageSpeed Extension [19]
* Use a code profiling tool ( XDebug[8], Webgrind [6], MacGDBp [7] )
* use mysql explain to identify if your queries are using indexes [11]

Backend
* Use gzip to compress output
* Check that server has appropriate CPU, RAM, Disk I/O available for traffic
* Optimize db query, proper indexing, joining
* Optimize php code
* Caching: Memcache [9], APC [10]
* Load balancing: web servers, db servers
* Separate out long running queries into individual tasks that can be
run on off hours or asynchronously
* Look into optimizing server configuration (trimming unneeded PHP
extensions, tuning mysql config, etc.)
* Switching to faster web server like NGix
* Use something like PHP-FPPM to make Apache run PHP faster [18]
* Thinking about changing some of your queries into stored procedures
that mysql can compile


Front End
* Minify Javascript/CSS files [3]
* JS codes at the bottom of page
* Important CSS files at the top
* Monitor 3rd party scripts (facebook buttons, twitter buttons, ad
networks). Consider async loading these after your page has loaded.[4]
* Add appropriate Expires or a Cache-Control Header[5]
* front end caching servers e.g. Varnish [12], Squid [13]
* css/image spriting [14]
* Progressive Jpgs
* Optimize (ie make smaller) your images, check out pngcrush [15] or
jpegran [16] for batch optimization
* Use Content Delivery Networks (CDN) [17]


Resources/Articles/Tutorials
* http://developer.yahoo.com/performance/rules.html/
* http://www.html5rocks.com/en/tutorials/webperformance/basics/

[1] - http://getfirebug.com/
[2] - http://developer.yahoo.com/yslow/
[3] - http://developer.yahoo.com/yui/compressor/
[4] - http://bit.ly/P6kde8
[5] - http://developer.yahoo.com/performance/rules.html/rules.html#expires
[6] - http://code.google.com/p/webgrind/
[7] - http://www.bluestatic.org/software/macgdbp/
[8] - http://xdebug.org/
[9] - http://memcached.org/
[10] - http://en.wikipedia.org/wiki/List_of_PHP_accelerators#Alternative_PHP_Cache_.28APC.29
[11] - http://dev.mysql.com/doc/refman/5.0/en/using-explain.html
[12] - https://www.varnish-cache.org/
[13] - http://www.squid-cache.org/
[14] - http://css-tricks.com/css-sprites/
[15] - http://pmt.sourceforge.net/pngcrush/
[16] - http://jpegclub.org/jpegtran/
[17] - http://en.wikipedia.org/wiki/Content_delivery_network
[18] - http://php-fpm.org/
[19] - https://developers.google.com/speed/pagespeed/