Even though “Deinterlacing” is unchecked, it seems you’re still running some detection code in the background to determine if you should deinterlace content.
This is an issue. It has been suddenly kicking in at about one third of a DVD to AVI conversion I’ve been trying to run.
Maybe what you need is an “Automatic” option in DVD to Mobile | Video Format, if you wanna keep running the detection code. But when in “Manual” mode, and “Deinterlacing” is unchecked, it would make sense that the problematic detection code remains turned off.
My guess is that it will also speed off encoding, but that is not the reason for this bug report.
Please let me know when you have a fix for this.