Sample Stretching takes too long

I have an issue that is so annoying. I stretch one sample and it stretches instantly but when I stretch another one it can take up to 1 minute to stretch it, so annoying when you have to slightly stretch 20 odd samples :-(

that's a lot of waiting.
In my video the first one I stretch does it instantly but why do I have to wait when I stretch the second one?

Here is a quick video of what I mean http://imageshack.us/photo/my-images/525/72lg.mp4

A work around is to use 'Resample' stretch meth...