Improve sanitize_post() calling

[johanee]

http://core.trac.wordpress.org/changeset/11282 resulted in a 5% performance regression.

sanitize_post() is called on every get_post(), which is used almost everywhere such as in commonly-called template functions (the_title, get_permalink, etc.).

A better solution than reverting the commit is to call sanitize_post() once only for a post: before storing in wp_cache_add() and for wp_query->posts. Instead of for example 16 times for each post in default theme.

This patch restores the performance lost by changeset 11282.

Only sanitize_post() once

Perhaps we can move the loop from _sanitize_the_posts() directly into WP_Query::get_posts(). That way it is run even if filters are suppressed and we avoid the pass by value overhead incurred by anything attached to a filter.

See also the patch on #10801 which avoids extra filtering in some places.

Updated patch:

• Call sanitize_post directly from WP_Query::get_posts() instead
• Also need to call it from get_pages()
• Included sanitize_post check from #10801 to avoid double filtering

Did not include get_post() part of #10801 which looked strange and probably buggy. :)

Only sanitize_post() once, avoid double filtering

That looks like the #10971 patch.

Only sanitize_post() once, avoid double filtering

Oops. Here is the correct one.

Revised slightly to avoid extra count() calls.

Ok, looking good! Performance for 10972.diff

Average total page load time (ab -c 1 -n 100 http://example.org) for new 2.9.0-rare install

1 post front page
org: 49ms
fix: 47ms

10 post front page
org: 115ms
fix: 95ms

Numbers are stable.

(In [12062]) Improve sanitize_post() performance. Perform raw filtering only once. Add filter check to eliminate double filtering. Props johanee. fixes #10972 see #10801