Win10 Issue
 

When someone zones into a zone i'm in (especially in force, like during a Raid engage race), my client lags/freezes for like a millisecond every time.

This didn't happen on Windows 7.

it is a hard drive issue, happened for me a lot regardless of operating system until I upgraded to ssd or used ramdisk software

But I'm using the exact same hard drive I had before.

I realize that, but conditions change. You may not even be able to recreate the non-stuttering even if you reinstall win7.