Best Upgrade Path for Large VST Projects

Hey all,

I currently have the following system:

DAW: Cubase 8.5 Pro
Audio Interface: Steinberg UR22 (1st Gen)
CPU: Intel Core i7-4930K 3.4GHz 6-Core Processor
Motherboard: Asus X79 Deluxe ATX LGA2011 Motherboard
Memory: Kingston HyperX Beast 64GB (8 x 8GB) DDR3-2133 Memory
Storage: Samsung 840 EVO 250GB 2.5" Solid State Drive
Storage: Samsung 850 EVO-Series 500GB 2.5" Solid State Drive
Storage: Samsung 850 EVO-Series 500GB 2.5" Solid State Drive
Storage: Samsung 840 EVO 1TB 2.5" Solid State Drive
Storage: Samsung 850 EVO-Series 1TB 2.5" Solid State Drive
Case: NZXT H440 (White/Black) ATX Mid Tower Case
Power Supply: SeaSonic 660W 80+ Platinum Certified Fully-Modular ATX Power Supply
Operating System: Microsoft Windows 8.1 Pro OEM (64-bit)

I do full orchestral score projects and hate freezing tracks whenever avoidable. I am looking for the best ASIO performance upgrade and am considering the following and am seeing which would be the best performance per dollar upgrade for VST/ASIO performance.

Option 1: Audio Interface Upgrade

I know the UR22 is a cheap little guy, but I don’t require a lot of I/O, only ASIO/VST performance, so would upgrading to something with reputable drivers like an RME Babyface Pro or an internal HDSPe AIO card help with multitrack VST performance?

Option 2: CPU Upgrade

Without dropping $2,000, I don’t know what I would upgrade to. The CPU I have, while an i7, is high speed/6-core, and the next “step up” in CPU is an 8-core Xeon at 2.0GHz.

Option 3: Vienna Ensemble PRO Slave Machine

The only other thing I can think of is getting VST off my main DAW. I could either build a secondary machine to use VE Pro and run that in tandem with my current build, or make my current build the VE Pro slave and build another machine to run the DAW software.

Does anyone have experience with this type of scenario/use-case and have any insight?