I'm waiting for fixing this issue(when enable deferred rendering).
It seems that this issue was fixed in these viewers.
Second Life 3.6.1 (278007)
Firestorm 4.4.2 (34167)
Exodus Viewer Beta 13.7.9 (1)
Singularity Viewer 1.8.0 (4114)
This fix has still its side effects?
http://jira.phoenixviewer.com/browse/FIRE-4725(Firestorm's jira)