Not sure if this has been fixed in FF2, but the current feature is that you cannot stab 2 seconds after getting a backstab. This can be circumvented by enabling advanced weapon switch, and just switching to your sapper (or gun) and immediately back to your knife in order to stab again lag-free. Particularly annoying because that's an easy 3000-4000 damage right there.
Not sure if this has been fixed in FF2, but the current feature is that you cannot stab 2 seconds after getting a backstab. This can be circumvented by enabling advanced weapon switch, and just switching to your sapper (or gun) and immediately back to your knife in order to stab again lag-free. Particularly annoying because that's an easy 3000-4000 damage right there.