I can confirm this. Stock browser on android (I have Galaxy S3) is fine, but latest Firefox mobile makes it impossible to scroll down any thread without this horrid jumpiness that snaps all over the place.
I've generally fixed this, though it seems like it's a bit of an issue with the core FF handling on mobile. It appears that FF basically won't let you scroll if the page height changes while scrolling.
Ultimately, this was triggered by our breadcrumb shrinking code, which ended up constantly triggering resize events - we really only care when the width changes. I've managed to stop that, but you might still see the behavior once one page load (where we already run the checks as image loads may have changed things) or if the page height changes for other reasons (share buttons, for example).