Hi guys.
I had crash problems with safe sleep (when the RAM is written to the HDD/SSD after a set period) on my old Air
Please find attached an article on disabling safe sleep via the terminal:
http://www.macworld.com/article/1053471/sleepmode.html
As a warning, once disabled, the Mac will not put itself into safe sleep to conserve power and if left for a few days, will likely drain the battery and lose the contents of the memory
however, it *should* mean instant wakeups every time.
There are instructions for re-enabling as well, should you dislike it 🙂
Hope this works!