I have had a look at your page and here are some comments;
The image is fairly hefty at 253kBytes. Checked the download speed and that was running at an average 23KB. If you are on a 512 connection then this is correct because the upstream rate is half your downstream. So there is 100% utilisation of the bandwidth and it won't get better unless you increase your connection speed.
Also have a look at gzip compression
and the howto here
. It may help other apps and probably not the image as this is already compressed. I run it on my server and I know it reduces the bandwidth utilisation, particularly when accessing database records off mysql.