I have the latest PS update, just installed the latest one a couple of hours before. PS is extremely slow in saving large files.
First, I had lots of troubles working with 412mg file. It was unusable. 20 seconds to highlight text, not responding when resizing layers, etc. savings took between 90-120 seconds. I finally deleted preferences and things are better however, saving still takes forever.
When clicking 'SAVE' I see the 0% progress for about 30-40 seconds, only after that I see the fast saving progress. When it happens it only takes bout 3 seconds to save.
I believe I have all the best preferences including 'disable compression of PSD and PSB files'.