I just wanted to mention that I have been working in a friends studio recently who is on a z170 chipset computer platform and I have noticed in his Cubase v8.5 that the Audio Tools cause GUI Lag aswell, but its not quite as bad as my situation on the x58 chipset computer platform. However his computer does not experience any 100% VST Performance drop outs. The point being is that I really do think there is something wrong with Cubase performace in its current state (v7, 7.5, 8, 8.5) Cubase v9 just release last week so hopefully there is performance improvements but yea this is not very motivating to waste money on a new computer with no guarantees that it will fix Cubase.
Windows, Intel, Apple, etc. need to seriously redesign how IRQs are handled, they only ever seem to cater to "graphic design" more so then audio.
For eg. I researched the new 2016 Macbook Pro and came to discover that it only has 4x Thunderbolt USB-C ports and a headphone jack, meaning that for audio people we have to use adapters and usb hubs to have any kind of audio setup and dongles and hubs never work properly and always cause issues with IRQs etc.
You will see youtube videos of graphic designers saying that the lack of USB 2.0 , 3.0 ports is no big deal etc, hahaha what the hell are they smoking seriously.
I am so sick of this BS, if its not one things its a fuc*n nother