Had the same problem. If I run P3d v2 as an administrator, the stuttering is limited and does not get worse, and you can finish the flight (even if it takes 2+ hours) . No hotfix 19 nor asc.dll change installed. AXE installed through the Estonia migration tool.
Outrageous by the way that after 6 months there is still no P3d v2 compatible installer. Most of their customers will be flying P3d and they still prioritize legacy products. Amazing business decision if you ask me. I hope they wake up soon.