Pre-processing in DVD Movie Factory 4

[emri]

On opening mpeg files, I always get the following message:

"The file has a better way to improve its editing performance. Do you want to perform pre-process to improve it?"

Does anyone know what pre-processing is?

Does it change the MPEG file itself?

Subjectively, I have found no difference, but I have not made extensive tests.

Is there any way to prevent the message from appearing each time a file is opened?