I have around 300 BluRay films. (I don't bother going to cinema I just buy the films as soon as they come out) and all but the 3D versions work grand.
I personally do not understand WHY ON EARTH sony left out BluRay 3D support when the PS3 was like a beacon for BluRay relieving support for BluRay formats from the off. The firmware update can not come soon enough.
Thank goodness most of my 3D BluRay sets come with the standard 2D version.
As for slow loading it could indeed be the BluRay interactive feature, just turn it off.