Steve Summit wrote:
On the subject of diff efficiency, which button is
more
expensive, Show Preview or Show Changes? I have an ultraparanoid
bot which "presses" one or both before actually submitting, and
it occurs to me that it would be marginally easier on the servers
if the bot used the cheaper one first. (Though of course only
if substantial numbers of its doublechecks failed, which they
typically don't.)
For whole pages, generating a diff takes about 2ms plus 40ms to load the
text to diff against, rendering a page takes about 800ms. So it's
cheaper to use "show changes" by a factor of 20. In fact, we've been
considering suppressing the "current version" display from diff pages by
default, especially for large pages, since rendering the current version
constitutes the vast majority of the time it takes to generate those
pages. These figures are averages based on latest profiling, some pages
take significantly longer than 800ms.
-- Tim Starling