The Little I Know – It does say ?? ??? ???? ??? ????, however, that does not warrant dropping a chavrusa. Watching indecent material can and does distract one from learning. It leaves a roishem. Smoking, whatever the issur is, does not harm ones learning (unless suffering from terrible addiction). No shuychus.
Heavy brisker – You may have heard from the Gateshead Rav, R’ Zimmerman Shlit”a at our many shabbos tables there, that every cigarette is an issur.