Does the Mask Feather tool render considerably slower than normal masks?

I'm doing a fairly long render with simple scenes.  Some use normal masks and some use feather tooled masks.  Frames from the latter scenes are taking over twice as long as their counterparts to render during final render.  Thoughts?

AE CS6 v11.0.2.12

PC, Windows 7 64-bit 6.1.7601
Intel(R) Xeon(R) CPU E5-2670 0 @ 2.60GHz

64GB RAM
Quadro 4000