which file is faster to work in scrivener

I would like to know which file: doc, docx, rtf, is faster in order to edit in scrivener, batch process, etc.

It actually doesn’t matter all that much, as all word processor files are converted to the RTF format internally. The software doesn’t actually natively work in doc/x. I’m not aware of any significant impacts to speed between importing/exporting any of these formats.