After searching through dozens of posts I found 2 things that drastically reduce the stutter/freeze issues if not completely eliminate them IF DONE PROPERLY.
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Download Starcraft - Inside the (programs X86) folder got to Starcraft>Support64 and find the file: Fmodex64_4_44_23.dll Right click and copy it and paste it to your desktop and rename it Fmodex64.dll.
1b. AFTER STARTING THE LAUNCHER, click the new Fmodex64.dll and copy/paste it into your Diablo 3 folder under (programs X86) and choose “replace existing file” -
START THE GAME NOW, once inside the game hit Crtl+Alt+Delete and open Task Manager. Right click on the “Diablo III Retail” and choose “Go to details”. Once it goes to details right click on “DiabloIII64.exe” and choose “Set Affinity” and then uncheck everything except CPU 0 and CPU 1.
I put a shortcut to my Programsx86 on my desktop to make this process easier. You will have to follow these steps every time you close the D3 program but I have only had lag once in the last month and I suspect my ISP was responsible for it.
The devs have been aware of these issues but I think their attention is more focused on new releases upcoming and less on an older game with almost zero revenue.
Good Luck!