A few work arounds:
- Delete all the unnecessary entities BEFORE importing into SolidWorks.
- Limit selections to less than 3000 or so entities if you need to move or rotate for example. Use point(s) on reference entity(ies) that will not move/rotate with the selection so you could move/rotate many selections and keep them in the same relationship
Hopefully someone else has some better methods.
Agreed with Chris - it's' been a few years since I did similar work, taking outside AC drawings and use them in SW. Absolutly delete everything you can get away with. Use blocks as much as possible...