For me, whatever changes happened to dynamic in 2.7.6 have made it work poorly again. It is back to being really unresponsive to lowering when I am using the gpu for other things. It will lower one intensity or even stay the same as when I am not using the gpu for something else. I am on Windows 7 with two 5870s. What specifically changed with the algorithm in 2.7.6?
(2.7.5 is running smooth, and responds quickly when other programs use the gpu, and all I have to do on that version is set the intensity to fixed then back to dynamic and I never get the negative intensity bug anymore. 2.7.5 is the first version since 2.1.2 that I can get high performance when not using the gpu for other things and still have really responsive backing off of intensity when I do).
I got rid of the long term history in dynamic intensity going into 2.7.6, as the long term history was occasionally getting a dud result and pegging intensity to some small value indefinitely. I guess I'll just have to keep reworking this till it works everywhere.
Maybe change it to "manual auto"? Let user choose 2 values of I and delay - when PC is on idle and when is busy. Then change lower intensity instantly when detected user activity and change to higher intensity when there is no user input over given time.