Guys...

I know for a fact if you want to write sector by sector from the beginning
to end of an hard drive, it may be very fast.

Defrag is very slow indeed.

I am wondering if there is some optimization that can be made to the defrag
so that data is pre-prepared in memory (just the meta data of course), and
once those pointers are ready, a major one-time-only set of writes occurs.

the problem I think with the slowness of defrag is that it moves blocks back
and forth.

I know I know, defrag must keep the disk consistent so it can not do a one
time operation otherwise a power failure may screw it all up....

but what do you think ?