Hi,
I want just chime in to give you some background on how VEP handles these things.
1. All plugins are responsible on how they share memory, or how they don't share it.
For example our player instances do all share as much memory as possible, things that can't be shared are GUI related as well as the instance settings.
You can test it by checking the memory difference when adding a second instance of the VI or Synchron Player and load the same instrument (if you don't have any VSL libraries to test it yet, there is a free version of the
Big Bang Orchestra available
).
But as soon as you add an additional instance in your DAW and load the same instrument, the memory can't be shared (at least on Windows with Cubase, it may work with other configurations, have not tested it yet).
There are also other players that also can use memory sharing and this feature should also work in VEP (for example: Play 6 does this if I remember correctly). You may have to test if this will still work if you host the same instrument on different VEP instances...
As far as I know current versions of Kontakt (5, 6 on x64) do not share memory.
2. It's always a good idea to have as few VEP instances as possible! Check if the thread count setting in VEP is set correctly (I have 6 CPU cores, I use between 3-6 VEP instances for comfort, thread-Count is set to 4 per instance, no performance issues).
If you use only one VEP instance you should set the thread count equal or almost equal to the core count. If you are using more VEP instances I would suggest to set the thread count to at least 2.
In case you are using only one instrument per VEP instance, set the thread count to 1; but this is really bad practice, so you should not do this (most users in support that complain about performance issues have this kind of setup).
3. You should disable the muli-processor setting in the Kontakt plugin, in case you have enabled it. By defaut it is disabled, the Kontakt manual suggest to disable it, we suggest to disable it. This setting can interfere with the multi-core / multi-thread optimization of VEP.
4. You can use Kontakt multis to save RAM, but design it in a way, so that you don't put CPU intense articulations / instruments in the same Kontakt instance. Each virtual instrument instance on gets processed by only one thread. In most cases this is fine because there is not much that can be processed in parallel within one instance.
If you are using multiple Kontakt instances to separate the CPU heavy things, VEP's thread optimizations work and will distribute the load optimaly on your CPU cores.
As long as you would not use a lot of Kontakt instances (hard to find an exact number, let's just say less then 50-100...), the better CPU performance is more important then the additional RAM usage.
5. It takes a lot of time to find "the perfect" setting for your system and your workflow. So don't try to get the performance up to 11. 80-90% optimizations will just take, let's say, ~20% of the time. Do more useful things with your time
If you have a decent system, stick to the recommended defaults and tweak a little bit here and there, make use of the instance disable feature on big templates, you will have good performance and a good time working with virtual instruments (there are always exceptions).
Bonus chapter: It is always good to know what your system is capable of. There are limits, but "upgrading" to the most expensive rig does not always make sense.
You will get a great complete system for about 1000€-2000€ (Windows machine, Mac is a little more complicated) that would be enough for almost all people here.
Sometimes we get support requests from users complaining about bad performance on their new machine with one or two CPUs which cost each ~2000€. If I look up what CPUs they have bought, mostly it is some kind of high core, low clock CPU for special web-server uses. These CPUs are good for a special thing, but not for DAW workloads. (Multi-CPU setups are generally a thing I would suggest to stay away from...)
So if you don't know what hardware will fit best for your use-case, contact a specialist. Even if you pay him, you will probably get a better system for your needs at a lower price compared to just getting "the best on paper and most expensive I can efford".
Best, Ben