That's an excellent suggestion Mike, although I think it will only give us a speedup when generating a new entry for the `_rootps_store` or `_rootps_whitening_store`, which hopefully only needs to happen every time the input image dimensions change or the `_BaseCorrelatedNoise` changes.

That said, for the `RealGalaxy` convolution we will be changing the correlated noise profile for *every* object, since the COSMOS PSF varies and we will often apply random rotations and/or shears.  This means a lot of time will be spent `draw()`-ing into a new array from which the power spectrum will be calculated before noise being generated (I'm actually slightly concerned about this...).

So yes I've convinced myself, I think that would be an excellent addition, if you have a chance...! Thank you!