Dashboard/Home Screen icons take up to 10 seconds to load after pressing the Home button
I have the same phone and pretty much the same issue(s).

First of all, you shouldn't be using a task killer. It's unnecessary and counter productive. (See this question and this other question.)

One thing that will help is using a Home Screen replacement. There are several, but I've been using Zeam. While it doesn't remove the homescreen redraw delay completely, it's much better than without it.

Another thing that will help is reducing or eliminating the number of widgets you're using.