Lewis & Short

per-quam, adv. (also, less correctly, written separately, per quam, v. per fin.), as much as possible, extremely, exceedingly: illorum mores perquam meditate tenes, Plaut. Bacch. 3, 6, 16: perquam indignis modis, id. Rud. 3, 3, 9: perquam breviter, Cic. de Or. 2, 49, 201: perquam modica, Plin. Pan. 60: perquam velim scire, id. Ep. 7, 27, 1: parentes perquam infelicissimi, Inscr. Murat. 953, 2: sagax, Amm. 14, 5, 6.
In tmesi: per pol quam paucos reperias, Ter. Hec. 1, 1, 1.