Perhaps its just me, but the image quality of pictures on websites when surfing via 3G/umts with vodafone really makes me sick. The images are blurred heavily just to save some bandwith for my flatrate 
After it now bothered me enough to take a closer look it seems t-online did it first and now vodafone does the same (proxying the images to much lower quality level). But at least for the firefox browser there is a workaround i found (besides reloading every page) that has no noticeable speed downside on my system but brings me full joy of websurfing back:
- Install “Modify Headers” add-on for firefox
- In “Extras” or “Tools” menu go on “modify headers”
- at the top select “add” (from dropdown menu), “Pragma”, “no-transform” (each without the quotes) and click the Add-Button next to it
- at the top select “add”, “Cache-Control”, “no-transform” and again click the Add-Button
- You should now have two rule entries each activated (a big green dot on their right side)
- close that window
- enjoy surfing
