superfetch

[David Cuthbert]

Jonathan Dama wrote:
Even worse [flash memory has] very slow write cycles + often can only
perform sector erase operations.
True, but sector-only writes are generally true of hard drives -- thanks 
to caching and smaller sector sizes, though, you generally don't notice 
this.

(You don't want to try to change a single bit when writing data on a 
magnetic medium.  It's impossible to line up the transitions exactly, so 
you will have residual effects from the previous data that will confuse 
the read channel, raising the error rate.)