Slicing holed object problem

[Ymmi 0]

So, I only started 3d printing recently and this is a second model I made. Its not perfect, but the geometry should be adequate. For some reason I can not slice it in Ultimaker - the slicing process freezes in the middle. Is it because of a lot of hoes in the model, or I've got a problem with topology?

Holed card.stl

[Ymmi 0]

Ok, finally sliced, but it took like 1 hour