Cloth emulation with collision dos not go well


I have cushion that I want to rest on sofa using physics modifier simulation. Would you suggest me how best to approach it? Thanks.

EDIT: I will expand a little more on the subject . For some reason of which I am not aware physics emulation is very slow. Collision enabled , cloth quality settings kept to a minimum and still FPS is like 0.03 almost standstill.
Then I modelled a very simple shape that reminiscent of sofa and the cushion as a separate file and bingo! It reached around 3-4fps.
Then I thought my original file is way too big and complex so I disabled all sofa parts, brought that simple-shaped sofa model and tried to recreate emulation. FPS was little better at around 0.3 but still bad enough to consider workable.
I will attach simple-shaped sofa file so you can see what I mean. I badly want to finish my sofa and hope you will come forward with your experience. Thanks!