For what it is worth-
Earlier this week we got a part from a client that took forever to rebuild.
Looking at feature statistics (under the tools menu) we quickly identified areas where we could astronomically speed up the rebuild time. I highly recommend putting feature stats on a toolbar and using it often - a case which I am about to attempt to justify
As delivered, this part had a 742 second rebuild time.
The most expensive features were a curve-driven pattern that took 557 seconds to rebuild, a fillet that took 85 s, and 75s, surprisingly, for a 'simple extruded boss' that should not have taken any time at all.
Turning off verification on rebuild (matt might want to pipe in here) the rebuild time was reduced dramatically on the feature pattern to just 28 seconds!!!, Oddly, the fillet and the 'simple extruded boss' only lost a second or two from their previous times (still over 2.5 minutes for the pair). I should also warn that there is a risk associated with turning off verification on rebuild because the geometry might not be any good and you could add work to a fundamentally flawed model- to avoid this without verification on rebuild, you have to manually check the model with tools>check or a round trip Iges export/import, but for the rebuild savings I have to admit it is justifiable on a part like this.
So, knowing all of that, how did we take this 742 second rebuild down to under 36 seconds with verification on rebuild still on?
Where we got the biggest gains were by restructuring the part so we could pattern bodies instead of patterning the features. As a body, the pattern took just a little over 3 seconds, and combining the patterned bodies took 26 seconds - all with verification-on-rebuild active. What is really interesting is that the 'simple extruded boss' feature, which was not touched, went from 75 seconds to a tad over 1 second. The fillet was irrelevant - it was incorporated into the patterned body instead of added after the pattern.
I just throw this experience out so you can keep it in the back of your mind - if your instincts are that the part is taking waayyyyy too long to build a) use feature stats to see where you are blowing a ton of rebuild time and look for anomalies (like that simple extruded boss). Old tip, but always worth another mention b) if a feature pattern is killing you, look for a way to combine the features into a body that can be patterned and see if there is an improvement. Even if the body pattern doesn't gain a lot, keep an eye out for other features that benefit from the new structure (the latter surprised the hell out of me)
Ed