Hi mir4ea - it's normal for any software to slow down when you give it a huge number of things to deal with.

But the default MoI display settings are more oriented towards making a heavier and nicer looking display mesh - with larger models those settings can be adjusted to make a coarser display mesh which will often speed things up by quite a bit.

That's what Mauro is showing above in his screenshot - in the Options dialog View section, set "Mesh angle" to 25 and uncheck "Add details to inflections" and see if you get better behavior after that.

That will degrade the display quality a little bit with surfaces being display with a smaller number of triangles approximating them but also gain speed. It should probably help quite a bit on something with a lot of little curvy pieces like your model has.

- Michael