This Python fix from @Atomvar helped to get rid of the slow-down:
in the w_mesh addons folder, go to __init._.py line 309 and delete ", icon=‘NDOF_DOM’ ".
It’d be great if the add-on developer could add support for adding a W-Mesh object oriented to the screen or 3D cursor. It would be even cooler if the objects could be added interactively on a surface, like QBlocker offers.