Please Help , Multires issue?

Hi I am currently a beginner at Blender 3D , i have been working with it for 3 days now although i have just run into my first problem.

I sculpted a head out of a sphere mesh and attempted to add in the nose eyes and so on. I needed to achieve smaller vertices in order for the small details to be added . Fortunately I tried the multires modifier and subdivided the head about 9 times , realizing that my computer could not handle multires levels higher than 8 i set the level to 7 but did not press apply. I created the small details and decided to paint my model.

I then proceeded to paint my model head although i could not achieve the full shape in vertex paint mode without first clicking apply. My head was now shaped and as i tried to colour the model i realized that the speed at which the multires levels had been marginally slowed and i was unable to continue to paint my model as the speed was lagging too much.

Is their a method to export then convert the model to a new file and import it back in so as to maintain speed?

MOST IMPORTANTLY:

What can i do in order to paint this model at its high multires subdivision? http://www.blender.org/forum/templates/baorg/images/lang_english/icon_quote.gif