apc, memcached, page, db & object cache enabled, but search is still slow

I’m using W3 Total Cache 0.9.2.4 on a dedicated server with nginx and APC and memcached enabled.

Page Cache: disk
Database cache: memcached
Object cache: memcached

For homepage, posts and pages everything is fast as lightning (almost). But when doing search (or something else that will not fetch the page from cache) the page takes about 1.2 – 1.6 seconds to be created.

To find out the reason, I’ve enabled debug info. And it says:

<!-- W3 Total Cache: Object Cache debug info:
Engine:             memcached
Caching:            enabled
Total calls:        4466
Cache hits:         4457
Cache misses:       9
Total time:         0.2191

<!-- W3 Total Cache: Db cache debug info:
Engine:             memcached
Total queries:      21
Cached queries:     21
Total query time:   0.0116

<!-- W3 Total Cache: Page cache debug info:
Engine:             disk: enhanced
Cache key:          _index.html
Caching:            disabled
Reject reason:      Requested URI contains query
Status:             not cached
Creation Time:      1.282s
Header info:
X-Pingback:         http://www.domain.com/xmlrpc.php
Content-Type:       text/html; charset=UTF-8
X-Powered-By:       W3 Total Cache/0.9.2.4

As you can see object cache takes 0.2191 seconds and database cache takes 0.0116 seconds. But creation time for the page is 1.282 seconds.

How can I find out why the page creation time is 1.282 seconds? It doesn’t seem normal.

http://wordpress.org/extend/plugins/w3-total-cache/