Update: I made some changes to the Quintic (and Lanczos and Cubic) initializations to cache the calculations that need to happen at setup, so they only have to be done the first time.  The timing script now reports:
```
$ python time_noise_pad.py 
time for test_corr_padding_cf = 28.08
time for test_corr_padding_im = 47.51
time for test_corr_padding_imgfile = 27.84
time for test_corr_nopadding = 6.79
```
So that helped quite a bit.  And since the _im pathway isn't cached, it makes your point about the ImageCorrFunc initialization even clearer.