Hi andras, was there something like a particularly large number of named items or layers in the 3DM file?

The other thing you can do to reduce memory size is to adjust the display mesh density to make it coarser, see here for some information on that:
http://moi3d.com/forum/index.php?webtag=MOI&msg=4196.2

Normally I would not expect for the Scene Browser to really make a big difference being open or not though - if that is what doesn't work well, can you possibly send me the file using one of those file sharing services, and e-mail the link to me at moi@moi3d.com so I can test with it.

105MB is getting fairly large though, you may need to just wait for a while when processing larger sized files.

- Michael