Comp settings are HDTV 1080, 29.97, Rendering in H.264 in AME with match source high bit rate, system Intel i7-3770K @ 3.50 Ghz, 64-bit, Geforce GTX 660. Effects are minimal. Using QuickDraw AEscript and some sharpen, and those are the extents of effects. No dynamic links with Premiere Pro.
Maybe I should have added that none of those have been different than previous renderings. The only time I've had this anomaly is after updating to CC 2014 from CC. The slowdown isn't congruent with effects used.