Firstly I want to say that before doing this test I moved all third party plugin away from pro tools aax folder, except for Softube Modular as I needed to have a common plugin to test in Reaper. Also, modular is very heavy on cpu and easy to stress the computer with.
It is to notice that I did not removed any plugin in Reaper. Both buffer were set at 1024.
Of course I opened the same instances (3) of modular with the same sounds. As I've used a templates I can say that the session were very similar.
So, I took a screenshot at the peak of the stress. In the screenshot is shown both the internal cpu metering of the daw and the computer one. Difference of such degree were totally unexpected.
Now, I cannot go further than this not being a tech guy and so, I will encourage some comments about it.
https://imgur.com/a/oF6PXES