Hery had working patch which allowed both PP/bloom and AA to be used together. Unfortunately Hery announced he is far too busy with his work and personal project to continue coding for FSO. However, we've sent a request he would at least send us diffs of the patches he worked on, including PP+AA patch.
This is not strictly a rendering engine related, but there should be increased focus to break the limits of being stuck to one CPU core. Every single new feature that gets added, slows the game down because not even the fastest CPU is enough for FSO as long as only one core is being utilized. To make things worse, GPU processing power is not used at all.
FSO would be incredible little beast if it could properly use GPU's and multi-threading. Of those two, GPU would give the largest performance boost I reckon.