That is great news to hear. Well as I recall, back when PT10 rolled out, AVID stated i7 & i5 was the requirement to run PT10. so I never bothered to keep up at that point. Apparently my processor isn't that level, but I see folks are still having success running the newest version on older Mac machines.
I am still running my Digi003 console, so I see this is viable since you are still using your rack (NICE).
So I should invest in a single 6 (CORE) ?, and which model ?, thanks again for your folks time out of your busy schedule.
Awesome you have a 003 because the latest drivers still work on High Sierra with Pro Tools 2018.X (its up to 2018.7 now) If you were to look at Avids compatibility chart, they will not state that the 002 and 003 family is "qualified" for anything beyond Sierra. Please note there is an important difference between qualified and compatible. Qualified is Avid tested it and gives it their approval, it is very possible to have hardware that works just fine even if it isn't on their qualified list. Even my 2009 cMP isn't on the qualified computer list but we all know it still runs everything well.
So I had a base stock 2009 model which I only maxed out the ram with, which at the time was 8GB (4 x 2GB DIMMS). So that means a 640GB HDD and 2.6GHz Quad core CPU (Nehalm) Here is a list of things I upgraded to make this machine comparable to buying something brand new
CPU: went from stock 2.6ghz 4-core (dont recall the CPU model#) to 3.46ghz 6-core (X5690). This in my opinion was where I saw the biggest improvement in Pro Tools for being able to handle heavy sessions better and overall much more snappy performance. I used an X5690 instead of the W5690 due to you could install more RAM if it were required (W5690 limits you to 48GB where you can get 56GB on X5690). The X CPU can be used in a dual and single CPU system, so if I were to make it a dual CPU system in the future I'd only need one more CPU. The W CPU is only compatible in a single CPU system.
RAM: went from 8GB using 4x 2GB DIMMS, running at 1066mhz to 48GB using 3x 16GB DIMMS, running at 1066Mhz. Please note if I knew better I would have gotten RAM that ran at 1333MHz due to the upgraded CPU allows the faster speed, however it is a very minimal improvement so not a big deal. Using 3 DIMMS is better than 4 because the cMP uses triple channel so when a 4th DIMM is installed you get a slight performance penalty. So my advice here is dont use more than 3 DIMMs unless you NEED more than 48GB of RAM and you likely will only need that unless you use a CRAP LOAD of VIs and samples simultaneously. RAM was actually the first thing I upgraded and saw ZERO improvement in PT8. So this may not help if you are still on PT9. Older versions of PT can only see/use a much more limited amount of RAM, literally only 4GB in PT8. So having more RAM is always great but will not be practical if you are on a PT version that cannot utilize it
Firmware: I think you stated you have a 2010 model which has 5,1 firmware natively. This is good, but if for some reason you have a 2009 model it has 4,1 firmware and needs to be flashed to 5,1 in order to due the above mentioned CPU upgrade. This is the other piece of the puzzle if you wanted to upgrade 1066mhz RAM to 1333mhz
Disks: I always used internal and external HDDs. Until I started reading up on SSDs and finally purchased one. I put a SSD in one of the SATA bays using an 2.5" to 3.5" adapter (got it from OWC). If you can afford it, use SSDs for everything. If that doesn't fit your budget, the best bang for your buck is to use a SSD for at least your startup drive. So this would be the drive that has the OS and applications on it such as Pro Tools. Everything is way more responsive and loads faster. I only use a SSD for my startup drive but lots of people use them for the drives they put samples on. That may not be practical unless you use A LOT of samples simultaneously. I do have my samples on a separate drive but it is just a HDD and it works fine because its only does samples for Superior Drummer 3.
OS: The 5,1 (or 4,1 flashed to 5,1) cMP models are still able to update to the latest HS version and people are even putting Mojave on them. They may not be supported much longer but will likely be able to be update through unofficial means. Regardless you can get to new OS versions that will run newer versions of Pro Tools.
USB 3.0: Since the cMP only had USB 2.0 ports this was a nice addition since I now also use a USB3.0 HDD and interface. Very noticeable difference if you are used to USB 2.0 and FW400/800
GPU: I did add in a newer GPU being a Sapphire Pulse RX580 8GB but this has no real world benefit to my knowledge for Pro Tools. The stock GT120 still works just fine, or whatever stock GPU you may have.