Is there a reason why it take so long to scroll down a chapter when you want to copy a lot of verses?

I'm not sure what you mean. On my 3GS it scrolls pretty well. It's not super-fast when copying, but I can copy a chapter in few seconds.

I hold down to bring copy up, then grab the bottom and start scrolling down to copy let's say a chapter, it takes a long time to scroll down.
This same thing happens on 2 of my 3 iphones(haven't installed it yet on 3rd phone), they both take a long time.
The 3G takes forever and the 3GS isn't too far behind.