I only sent the test to a couple of people who had definite symptoms of the issue I suspected.
I know now that the OP's problem is directly related to this since it fixed it for him. We'll address this for the next update since its not a widespread issue and for now there is an easy way to avoid the extra load.
The good news is that even after that fix we found a way to optimize dynamic arm even more.
Now even in the worst case scenario with ALL synth ports active, the CPU load is minimal. We shaved off over 40% of the dynamic arm load by doing some optimization analysis and this second optimization will improve dynamic arm CPU performance across the board. We have a ton of new optimizations as well coming up in the next update as well so lots of improvements in this department.
Thanks everyone for pitching in to help figure it out.