Page speed improvements (general)

[Vanhouttethomas]

As a result of a lot of images, a lot of HTTP requests exist to load the page.
Since we now also target mobile users (responsive design), we should minimize these requests to decrease page load times.
My sugguestions:

HTTP REQUESTS
Put all images in one or more CSS sprites to reduce HTTP requests.
Or, use DATA URIs.
Also, less important, combine the CSS files and put them at the bottom of the page.

IMAGES
The images themselves are quite large. They can be easily compressed by 50%, while maintaining the quality of the images.

CACHING
Images are not cached, nor other static sources such as the Javascript or CSS files.
Use page caching to cache these for (for example) 2 weeks. If a visitors visits the page again later, the page will not have to load these static sources any more.