Can you really in some way mimic the reduced download speeds of my website, as if it's located on the web server, but from my localhost?

It's difficult to check such things as Ajax loading symbols once the content loads so quick out of your local machine and so i think this may assist me a great deal?

I'm wondering if there is something you could use with this or if you would want to use javascript to include setTimeout or setInterval code?

If you work with Home windows, then download the Fiddler tool Fiddler.

This can setup a HTTP proxy which you can use for testing HTTP headers and examine all of the HTTP traffic inside the PC and browser. After that you can make use of the Rules > Performance > Simulate Modem Speeds choice to slow the browser's HTTP connection.

There's additionally a Fiddler Switch plug-set for Opera open to toggle the Fiddler proxy.

If you are on the *nix platform, you can affect the 'nice' level to essentially build your process an afterthought behind most others before you achieve an amount of 'lag' that's acceptable for your needs.

To begin with, please never mangle your code with if ( DEBUG ) workSlowly() claims. You're going to get bitten with this practice, and it'll hurt.

Secondly, use among the traffic throttling solutions which have been published here. I am likely to give a Java-based solution: Sloppy. It's dead easy to setup and runs everywhere where Java runs.

This will let you out.

Personally, I add something similar to this towards the top of my library file or whatever file always will get incorporated:

if(DEBUG) 

The above mentioned is PHP, but many languages will have such like.

One choice is (if you're on linux, but other unix system have similar tools) Traffic shaping (google for 'HTB', 'qdics' and 'tc' command)

Second item is going to be apache_mod_cband module, this is most likely easer to begin.

You could attempt Charles. It's mix platform - I personally use it and delay pills work very well.

http://world wide web.charlesproxy.com/

On home windows you should use Proxomitron or else you can install fiddler (for ie). Both allow you to set the data transfer speed.