I really need to use more than one instance.  I use one instance for cymbals, one for kick, snare and toms, and one for percussion.  I have 16 gigs of RAM which should be enough.  My Sample drive is petty full so I'm going to try changing that.  At some point I'd like to try an SSD since prices are coming down.

I don't understand why so many instances, you can route each channel of each kit piece to separate tracks if you wish. What can you achieve by having a separate instance for kick and snare that you couldn't achieve normally ?
 
You can have a 32 piece kit in BFD2 which AFAIK is more that any other drum VSTi that I know of.
I've only ever heard of people wanting more than one instance when they have gone past the kit size limits
but that almost never happens in BFD2. BFD3 has doubled that and now gives you up to 64 kit pieces (I think) or certainly more than 32 as I have just made one.
I'm seriously intrigued as to what can be gained by using one instance per kit piece, that just seems insane to me and needlessly complicated.
Sorry, I'm sure you have good reason
 
Steve

Here you go, from the bakers..
 

How big can I make the kit in BFD3? [top]
The kit in BFD3 is limited internally to 64 pieces with a maximum of 5 Drums from each Drum Class.

To achieve this kit size you must have enough system resources and you must be able to map all required articulations to notes within the 128 key range of a MIDI channel unless you only want to play the kit with BFD3's built-in Groove engine, which internally addresses each articulation directly without using MIDI notes.

 
 
I like that, BFD3 is LIMITED!! to 64 kit pieces. Totally inadequate  
When they say "5 kit pieces for each class that means you can have 5 floor toms, five hi-hats, 5 snares, 5 mid toms etc. etc.
 
Steve

I have a meticulously compiled set of cymbals that I use on every kit which takes up 13 slots.  I use the same cymbals with AD and SSD. The kit instance only has bass, snare and toms.   It would be insane to set up that cymbal set for every new kit I create.  Also when auditioning kits for a song there is no way I want to wait for all those same cymbals to load.  This way all I have to load is bass, snare and toms.   The 3rd instance is percussion.  I have many percussion kits set up for e-drums that I can instantly call up and play.  They took a lot of work to set up.  This would be impossible with one instance.  I'm a drummer and I've worked this way for years.

But that's still less than 32 pieces and I don't know how fast your system is but on mine loading 13 cymbals took me just over 15 seconds (I saved them as a preset) and I thought I was impatient
 
Anyway, as long as you're aware that fxpansion don't recommend loading more than one instance and that "may" be causing problems there's not much more I can say. I'm guessing the problem with BFD3 and cubase locking up happens when you have more than one instance of BFD3? ? If so you could try usin one of the lower spec profiles that can be found in the engine preference tab and see if that helps.
 
Steve