Is there any way to detect if a computer is slow and not run some code (by either turning jQuery animations off or just running a function if it is fast)?
I kno
i think there are two options:
Let the user decide - give a 'low bandwidth/low spec' option to the user which when clicked will display the simpler version of the site.
Try to detect slow machines - you could try to detect a slow machine by using a timeout script - if the animation/loading doesn't complete within a certain time switch to the simpler version of the site. The downside to this method is that you have no idea why the script timed out - perhaps it was a bad connection or the user was loading something else at the same time temporarily slowing their machine.
Hope this gives you some ideas.
Josh