Ulead video studio 11, how to disable preview?

Hello there, I have Ulead video studio 11, a very fine piece of software. I have many MPEG files, about 30 min and want to remove some parts of each ending to about 25 min.
At first, the application used to do the process pretty fast(~5 min). For some reason, lately, it became too slow (exceeding 40 min) on the very same machine, with the very same applications in the background.
One thing I noticed, is that when it became that slow, it was showing a preview of the file being created. when it was fast, there was no such preview.

could that performance affection be related to preview?? I searched EVERYWHERE, but didn’t find a way to disable that preview. Please, I don need help if u can.
Thanks m8s

Why don’t you ask the creator of the software?