Stuttering Everything on New 5K iMac

I have a brand new iMac 5K (2017) with 16gb of RAM and 1TB SSD. My Windows 98 PC (20 years old) performs smoother. Everything in Safari (and my software) stutters - like the refresh rate is 15hz. I did all of the typical things like SMC reset, loading OS from "not" a backup, hardware test - and nothing changes. I do audio editing (Wavelab 9.5) and the cursor is not usable - it's literally 6-dimensional. It's almost like I can see the refreshing like I am fanning through a deck of cards.

Apple Support said it's not normal and will have Senior Service Support call me. I don't want a brand new computer hacked open at the store and glued back together. Is anyone else having this problem? Doesn't matter if I am in Safari or Chrome - same thing. Doesn't matter what software I am in, same thing. Again, it's like a fast flicker. If it was a flicker test, I would say it flickers great - but - is anyone else having a different experience? Does your screen scroll smoothly or is it jagged? Cursor - smooth or jagged? This happens no matter the display settings of "more space" or less.