Sorry! I actually meant VI within Logic, as in I load VI pro instances directly to my midi tracks. An exception is Dimension strings where I load a VE per section. 

I have this observation:

When I started with VSL, I only had the SE vol.1 and plus. I was loading everything to VE, and I had something like 3 VE instances with around 48 tracks in total. Then when I started using Dimension Strings and Brass, the track count multiplied and I had to have quite a lot of instances of VE.

Then, when I was trying out MIRx, I downloaded the demo song for it. I've realised that every instrument (41 in total) was directly loaded to a midi track as a VI pro instrument, bypassing the VE completely. The performance was quite good, so I did the same for my template. I still don't exactly know what would I be missing out by not using VE, other than the fact that in VE, all the instruments are at the same place, easy to find. But I don't mind that in Logic.

Then, I did the following test: I put 16 Dimension Violins to a VE instance. When I record all of them simultaneously, Logic was using just one core. When I played them back, Logic was using just one core (even when I select a stale audio track, for example). The performance was obviously not so good. Then, I loaded the same instruments directly as VI pro instances within logic, so one VI pro per midi track. When recording, Logic again processed them in one core, but when I played back, Logic used all the cores (or I should say threads actually) equally, which resulted in a better performance.

I searched through the forums to find out about any performance increase in using VE pro in a single computer, but I couldn't find any. I would be glad if some one can point me to a thread where I can read about it, or write their own experiences about it because from what I could gather, if I compare using individual VI pro instances to using VE pro to host everything, the difference only seems to be the fact that VE pro is more organized, and one does not need to reload samples when one changes projects etc. with VE pro. 

But I think, when one uses VE in a track in Logic, and uses 16 channels (=instruments) within that, Logic seems to treat that whole VE instance as a single instruments and processes them in a single core. But I only monitored this in Logic; it is possible that the VE server is redistributing that load in the background. 

Did anyone else try using VI pro directly as an instrument in Logic? Or what else may I be missing?

My last query is a mistake from a mistake reading. I though you were, in addition to using something other than VE Pro on the network one way, both ways.

The only thing I can even guess as to knowing how many cores is used is Activity Monitor, % of CPU per application.
 I already saw your claim.

From my understanding, 'all 12 cores are being used' means you are seeing in all over 1100% of CPU for VE Pro in Activity Monitor. My understanding could be mistaken, but I know that 'it's easy to monitor the load on all the cores' definitely does not help that understanding.

Ok, thanks. I don't know what to make of those graphics though. It is using more cores than I believed I think. Some of the green areas are not very tall and with Cubase not playing back two of them do not indicate the system is using any, then there is slight usage. I could maybe convince myself that the 14 I have assigned are being used and the 2 that leaves Cubase are then used, but I wouldn't want to argue that.

I'm not having pops and clicks but my latency is maxed out. What it will do with more to handle is simply drop out. Maybe more cores would work.

IN fact, though, I added another instance to test something to help another user and forget to give one of the instances I'm using two cores I borrowed from it back; and I got drop outs, which abated when I gave the two cores back.

The 'history' window looks like 8 cores are being used around twice as heavily as the rest; every other one used half as much. I guess the virtual cores.

I see. I still would like to believe that VE and VE pro have the same base program, and VE pro has additions like networking and using one instance for many projects. I think one problem I realized is that, when VE is used as an instrument in Logic, Logic basically treats it as a single instrument no matter how many VIs there are in that VE instance. I still need to test it though because I only looked at Logic's cpu meter. But if the standalone VE has poorer performance than the Pro version, it means that there are some programming things under the hood that are actually different. 

Which brings me to this:

In the evening, I will try routing Logic to a standalone instance of VE via IAC to see what I can do. Actually, I can't work without freezing tracks with my current rig, and if using VE pro through IAC is preferred for Logic/Mac setups, it's not going to help me much. But I'll just test it and write here what I find out. I hope standalone VE and VE pro are behaving similarly.

(I wish there were some kind of benchmarks about these things. It would be great if there was something like "recommended settings" and measurements for different kind of PC or Mac configurations.)

Also, if VE pro is absolutely necessary to get a proper performance from VSL products, I guess I might consider getting a PC slave and using my Macbook pro in the clamshell mode as a master. But I would really like to have a one machine setup. Let's see! I'll be back with some observations. :)

Thanks for all the info so far, it's really helpful!

I meant putting the VE connection to the "instrument" slot of a software instrument track in Logic, as opposed to running the standalone version. I didn't know how VEP is used and I thought people were using the standalone version but I was wrong. So, you're right, when I use VE, the core distribution seems to be handled by VE. I realized that the CPU meter of Logic and the CPU meter of the activity monitor are not the same, and VE distributed them equally to my 4 threads.

I also tried connecting to the standalone VE through IAC and route the sound back via Soundflower. The performance was worse than using VE server. So I'm back to the beginning. :) Later on, if I have the time I'll try to demo VEP and compare it, but I think I should get a somewhat similar performance.

However if you ever do VE Pro as audio input, it is now an external device and printing its result offline doesn't happen, it's realtime or nothing.

Standalone, that is something other than a plugin and it does not use the LAN to talk to other modules. The model for 'standalone' is really Gigastudio which got MIDI into it from, and audio back out of it to, the sequencer by external means. Cf., Kontakt used as a live instrument connected to controllers and audio out to amplifiers. I don't know why someone would connect a DAW to a standalone VE, don't need to know, don't care.

"don't care."

Ok, as to IAC. First, @ Oguz, the reason you do not need Soundflower is that VE Pro is already getting audio back to Logic, whether through gigabit ethernet or local host. Typically using IAC, one does not have this going on.

Cyril: You believe it's more efficient to send MIDI through ports in IAC to VE Pro than through VE Pro.
How, why? So far you seem to have asserted that through being internal to the OS it is. That doesn't show me. I can equally find someone saying that IAC isn't priority to the OS like VE Pro.

IAC would be a thing for a Logic person as you get additional MIDI ports through it rather than this Event Input kludge. I hadn't given it any thought but given that, I think if I was using Logic for VE Pro I would be doing IAC to some extent.

It's not hard to believe it's better than Event Input. However I don't need Event Input, I'm using it as VST 3.

To your last question, yes.

https://www.youtube.com/watch?v=0Ida0KB34kk

This shows how to do it. You're replacing the output with IAC Bus. It's easier than this in Cubase, it was just a matter of enabling IAC and it appeared as a choice in MIDI output and then enabling it in VE Pro, after a restart it appears in the ports assignment.

VE Not-Pro - edit: *SERVICE*, what you connect to as plugin - apparently has no option for external MIDI so IAC isn't possible. Yes, that is a difference.
Note: it's the getting audio back to the DAW that has me caring not at all about its (standalone's) performance, here is too many moving parts to even remotely consider. Since I believe VE Pro does what it says on the tin in the first place.