We have found that after installing SP1 for Inventor 2013 is nearly impossible edit derived assembly. It takes very long time for open dialog of Derived assembly, without SP1 it takes approx. 2mins. for assembly of 20000 instances, with SP1 it takes more than 2 hours! This we are able to reproduce on each of our station. And more, there is still not corrected bug with save setting of hole patching range. This setting does not remember min and max value and after re open this dialog the range is set back to default value 10-9999mm.
I have tried ti disable antivir and all unnecessary services - no effect.
Inventor 2013SP1, Win7SP1 64bit, Eset Endpoint Antivirus 5.0.2126
When using the common assmebly to make derive, it looks fine when editing the derived assembly. Maybe it is related to the dataset you have. So could you attach the dataset or send me @ email@example.com for further investigation?