Sudden poor viewport performance on wireframe mode

Hello BlenderArtists,
My viewport perfomance in wireframe mode has suddenly decreased to an unusable state. Panning and rotating moves at 1fps. The thing is, it works flawlessly in solid viewport shading (or even texture, material and renderer shadings). The scene is around 40MB and has 80k faces (160k tris). I am running it on Core i7 4710HQ, 16gb ram, gtx860m and Blender 2.75a.

Any suggestions,
Thanks.

ahh… thats blender for ya…

sorry I cannot be more helpful, but blender has bad viewport performance…

try using “local” view, to see only 1 object at a time. (press numpad /, with an object selected.)

Not a great workaround, but I resort to hiding parts of the scene other than what I’m working on. Try hiding verts you aren’t specifically using. H key hides selected vertices. Alternatively select the vertices of interest, press CTRL-I to invert the selection, and then press H to hide. Another way to temporarily simplify a scene is to put a single object on its own layer until you’re finished with it.

Shift-h hides not selected.
But there is something different going on. 160k tris is really nothing to damage performance to 1fps. Here, on 2 core AMD CPU it takes 3M tris to degrade to such ‘performance’ while showing wireframe.
Incidentally, compressed blend is 40Mb.