I just did a quick check, and the unanimated icons are between 1/2, and 1/10th the size of the other icons. Of course, only a couple of the icons are more than a kilobyte in size, but if a thread gets large, and a lot of different icons are used, the difference could add up.

Of course, it won't decrease overall site bandwidth (much) because it represents very little in terms of aggregate bandwidth....but even if you ignore the bandwidth issues, it simply slows down the end-users experience a bit, especially if on (god forbid) dialup.

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paul@pleaseohpleasedontspamme.slcentral.com
A mathematician is a device for turning coffee into theorems -- P. Erdos