This is what Puran has to say:

Boot Time Defragmentation
Some of the files like MFT, Registry, Pagefile etc cannot be defragmented or are not safe to defrag when Windows is running. This is when Boot Time Defragmentation displays its benefits, defragmenting these files at Windows Boot Time and getting optimal results.
Puran Defrag provides a very powerful Boot Time Defrag that defragments not only the system files but the entire drive, giving you the maximum benefits.

Source: Puran Defrag - Automatically Defrag your Hard Disk Drives