Based on my latest tests I can affirm that is a kernel bug.
Androxide 3.0.0 comes with default JB kernel .31, where this bug don't happen. Top battery usage goes to Android System (surfaceflinger).
JellyBelly comes with _thalamus .38 kernel, has this bug. Top battery usage goes to Phone (RILD/RILJ).
Androxide 3.1.0 comes with AirKernel, also has this bug but with less ocurrences. Battery usage split between Android System and Phone.
With the decision of _thalamus to make a based .31 kernel, I guess soon we'll have the best kernel ever made.
EDIT: Sorry for the references to "Nexus S" content. I know this is a Galaxy SII forum.
Sorry for my sh'tty english.
Nexus S running JellyShot with Marmite kernel. (Keep it simple!)