From Toronto, Canada to Houston Texas there where 4*200ms delays (nearly 1 second) on the first traceroute. A second test reduced that to 5*50ms which is much more acceptable.I also noticed that your sundance.jpg image is twice the size that you are displaying. Saving your 640x480 file as 320x240 would also have a slight effect.

Finally, without bothering your server, I have no idea what you are using or how it connects to the Internet. If you are hosting it from your own statis IP you are probably being throttled on the upload (~5-10 mbs down and ~.6-1 mbs up).

Yes the server will take a moment when it has been idle, but it's a one time performance hit.  After that it should be repsonsive.

Keep alive might help with the initial hit, but on a slow site it just wastes energy.