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pontifex - 6:29 pm on Nov 23, 2009 (gmt 0)
Let me summarize some of the points, I hope are helpful to anyone concerned about "loading speed": Basics The loading speed of a page depends on various factors - some are easy to control from your side, some are not. Before you tweak around on picture sizes, length of style sheets or Javascripts - test your hosting location for speed in general. It helps if you know about some static pages of other companies using the same host... Tools to find out about the network profile of your hosting companies are basically:
Folks, some of you have been on my session I did on Pubcon about loading speed and how to achieve that on a shoestring budget.
which are available on Linux servers and also on sites, which provide a web page interface to these tools.
Test your route to the domain/ips your pages are on from different websites with these tools and a good roundtrip time for a package of data sent to and back is measured in milliseconds and below 100 ms!
If you are with an unstable host or on a blade server with your VPS that is constantly overloaded there is NO way to improve that other than MOVING!
Then configure your webserver right. With Apache there are 2 basic configuration modes and 1 very important config option:
a) deliver on persistent connections or not
b) maximum concurrent connections
The best values differ from site to site. There is NO perfect default value!
ADVANCED
Once you made sure you are with the right hosting company (pricing is NO indication of quality here, by the way) you may start to work on the real factors that are within your reach.
First understand the amount of requests sent to your webserver by requesting a single page:
widget.php
normally also triggers
widgetlogo.gif
widgets.css
widgetswitcher.js
avatar.jpg
etc...
So a single page may trigger 20 requests to your webserver and your webserver does not like that at all! 20 requests per second could make the next visitor feel an additional delay of 1 second easily!
Install "firebug" for Firefox and watch the net statistics while you reload pages. Hold the shift key while doing so, or you will hit your local cache!
If your page takes more than 5 seconds on a DSL or cable modem line - you have to do something!
I achieved satisfying results with reverse caching, using SQUID - an open source product that I put between my surfers and our main servers. This may or may not be the solution for you! Sometimes it also helps to put images together in one big file (keyword: sprites with DHMTL), optimizing your database (sometimes a blog with a badly configured MySQL setup could draw your whole server down), packing 5 external javascript files into 1 and compressing it or other hints can help a lot.
This is just a first start and to really have a real fast loading site: it is a process of optimization over time - I look at speed like once a week and try to come up with something to improve it. After a few months you will be there and you will see your conversion increase and more people coming to your site!
P!