Hi Speed, thanks for the bug report.

It's going to be a bit tough to totally track down what is happening there since I can't reproduce the issue over here.

I presume the iges file is really large? Are you willing to put it on a CD-ROM and snail mail it to me? If you are willing to do that, I could then examine it over here and try to solve the problem.

Switching to running extremely slow is generally a symptom of RAM being completely full and having hard-disk swapping engaging.

But it is odd that it is triggered by zooming in. Is it when you zoom in especially tightly?

Normally I wouldn't think that zooming in would trigger a big spike in memory consumption - the only thing that I can think of that would be effected by a zoom-in is curve drawing (because the shaded surfaces have identical data regardless of zoom factor). I guess that curve drawing is going crazy on something in your model and spiking up in memory usage. Curve drawing is actually a pretty intensive procedure, a lot of time it actually takes more crunching than surface drawing for many models.

For now you may need to only work on a portion of the file at a time.

- Michael