Hi mir4ea - no, 64-bit-ness does not really do anything to help with speed, it just increases the maximum amount of memory that can be used.

You might try adjusting some display settings, by default MoI makes a pretty dense display mesh and if you have a heavy model it can be better to make a coarser display mesh instead.

To do that go to Options > View > Meshing parameters and set "Mesh angle" to 25 or 30 degrees (instead of the default 10 degrees), and uncheck "Add detail to inflections".

That can help to reduce memory consumption and increase display speed on more complex models.

Also if your model is particularly complex you may just need to hide chunks of it instead of having the whole thing displayed all the time. If you want to maintain a reference for some things, you might also try hiding just the edges of some objects, often times the edge display takes quite a bit longer than the shaded surface display does.

But definitely try the coarser display mesh settings.

- Michael