It should now be REALLY fast in comparison - about 10 seconds
Edit: It seems to depend on how much memory you have available. On lower specs it seems to stop at ~80% and start crawling. If you have enough memory it does it all verrry fast.
Once the texture is loaded in, I run blurring on it before doing anything else.
The result is far far superior..
The only issue left to deal with is that at higher resolutions chrome runs out of memory and the whole thing slows down considerably. I don't think there's any real fix to this - v8 engine has a memory limit built in.