I have a really simple compositing flow with just the render result connected to a lens distorsion, and I connected a mask so I can control its effect.
But the performance is incredibly slow, when moving any point of the mask curve, it recalculates everything. It’s impossible to place a point accurately because it lags so much.
I can’t believe that people worked with such bad performances on Tears of Steel, so I must be missing something. I activated Open CL, changed performance settings in the compositing but that didn’t really help.
My image is a bit smaller than 1080P, my PC setup is pretty good (i7 3930k @ 4.2GHz, GTX 580 3GB, 16GB RAM), using Blender 2.71 on Windows 7 64bits.
PS: Also another question: I’m missing the “alpha” input of every filter node, like in other compositing software. There is no such thing in Blender? For now I multiply my mask was a value then connect it to the lens distorsion value, but that seems a bit complicated to do this everytime you want to mask an effect.