They have to be coupled to add that time not decoupled.
Right, I remember that. I used to have 6 external sampler PCs that all ran decoupled VE Pro servers and project save times were pretty quick.
On my system I have Vienna is decoupled until I do a final save to cut down on save times. Thus when the Kontakts are on Vienna the save is very quick. However, I can’t use vienna in cubase 8 without turning ASIO guard off and that makes things rather difficult with even just a few processors running.
These long saving times are …grrrr…so annoying… I have 10 sec or so for saving an empty project, with no audio, midi events, nothing. Just loaded my template with around 40 Kontakt instances full of instruments ( every instance with 8-16 instruments, samples all purged). Around 250 midi tracks / 100 kontakt outputs.
I did some testing…all those instruments loaded in Kontakts ARE the reason for long saving times. If I unload them, and leave all kontakt instances empty, all the midi tracks, audio outs and all plugins (every audio out has instance of virtual scoring stage 2) stay as well, instant, less than sec, saving times are back.
Maybe samples are not the reason… even when we purge all samples, our ram is occupied with other instrument data…what ever those are 
But, yeah, still no reason Cubase don’t behave like other daws regarding this, cause waiting 10 secs every 5 minutes is good reason for changing DAW, indeed…
Same problem here, only with Play instead of Kontakt. But I’m not talking about 30-40 seconds, but upwards of 2 minutes!
And it’s not because I’ve got such an extremely large template. 18GB ram in total. Reaper did this absolutely just fine.
It really is frustrating because the rest of the program is snappy as everything.
If they’re loaded internally they’re automatically coupled aren’t they? Unless I’m mistaken, Vienna, not Kontakt has a decoupling option if you run it outside Cubase and link it.