specs explaination/detailed description

hi;
i read the rtx51 specs on the site.it
gives context switch for fast task as
70-100 cycles.does this difference come
due to priority polling?secondly does
context switch is equivalent to 'dispatch latency' form qnx manual?i
am asking this because dispatch latency
is composed of some other factors plus
context switch time.
your reply is eagerly awaited
pranav phatak