When you say load, in what environment are you requesting the asset?
I have (weighted numbers) something like this for a 250 kb jpeg:
Author: 100 ms
Publish: 75 ms
Dispatcher: 60 ms
CDN: 25 ms
That is on a single image request on one page. Requesting multiple images on one page adds quite a lot of wait-time for getting requests through, since only 3 concurrent requests are allowed to our environments at one time.
I am getting this responce in publisher envirenment and in comparison with your above example, 20 kb jpeg image takes 2 sec to load in my case