We prove a degree 1 saving bound for the dimension of the space of cohomological automorphic forms of fixed level and growing weight on SL2 over any number field that is not totally real. In particular, we establish a sharp upper bound on growth of Bianchi modular forms. We transfer our problem into a question over the usual universal envelop- ing algebras by applying an algebraic microlocalisation of Ardakov and Wadsley to completed homology. We solve the representation theoretic question by estimating growth of Poincare–Birkhoff–Witt filtrations on finitely generated modules.