I have an interesting problem, I guess...
First of all, I want to use sprites, to reduce the HTTP request on my site. That is because I know it's better for SEO and it makes the site faster, most of the time.
The interesting thing, though, is that my sprite is bigger in size in comparison with if I use four separate background images. The sprite: 20kb vs. 10 kb if I use 4 separate images.
20 kb vs. 10kb = 1 request vs. 4 request.
What weighs more?
P.S.: the background images are used because I want to distinguish the posted forum; so not essential, but I found it necessary.
P.S. 2: I know it's better to use <img> tags with the alt attribute, but I haven no choice in this one, because it's conditional.