Slow bootup in MacBook Air, Windows & Bootcamp
Other users have also faced the same problem and have suggested:
1) Reset NVRAM
2) Reset master boot record, partition info
3) and many others – a quick Google search will reveal many such fixes
None of these worked for me. I started taking a fresh look and figured out it was a problem with the MacBook and not my Windows setup.
Further research revealed that MacBook tries to find the bootable volume and that takes time. If the default volume is set then it would not take time.
To solve this problem, launch Windows 7, run Bootcamp From Control Panel. In the first screen select the windows volume and set it as default startup volume. Click ok to apply changes and restart.
Now the startup time is reduced to 5 seconds.