[TYPO3-core] Speed up of page cache

[Dmitry Dulepov]

Hi!

I was able to speed up page cache quite a lot by adding index on "expire" field
in cache_pages. One moment a single instance of mysql 3.23 started to get around
400 request/second and sites were running slowly. Immediately after altering
cache_pages table with phpMyAdmin it ran significally faster.

I do not know where cache_pages structure is defined but it may be good to make
such change there.

Dmitry.