WordPress has lot of good themes that we can choose from. However, if you are using old WordPress Theme likes mine which has lot of small images. CSS sprites will help to improve your blog loading speed. What are CSS sprites? A sprite combines multiple background images into a single image. This is a technique for making web pages faster because it reduces the number of downloads in the page.
Yes, the more images in your WordPress Theme, the more HTTP requests to server will be made. Therefore, the slower your blog will be loaded.
CSS sprite that use in spBlogger.com
There were 11 images before I combined them into 1 image as above. As result, I managed to reduce 11 HTTP requests into only 1 HTTP request. This will reduce web hosting CPU usage too as lesser requests are made.
How to speed up WordPress blog with CSS sprites?
SpriteMe is a great tool to help you. It is even better if you have CSS knowledge. Else choosing a good optimized WordPress Theme will do the trick.