"Jittery" HD picture with TiVo HD 9.1?

Ever since my TiVo received 9.1 (and I got my cablecards working again) I've noticed that sometimes the HD picture will look "jittery". The best way I can describe it is that it looks frames are dropping out.

I've also noticed picture freezes. They only last less than a second, but can happen several times in a row.

Has anyone else noticed this problem? Could this be related in general to a signal processing problem with the 9.1 update, as evidenced by the return of the pixellation issue for some people?