Not getting improved performance from Memcached - php

Question

I have a prestashop based ecommerce website (GoDaddy Linux Centos VPS). I'm trying to cut down on what pingdom calls "wait time", the time it takes for my server to generate the html through php and mysql.
I believe I have memcached installed correctly, but I am not getting improved performance, when I have it enabled.
What's going on here?
STAT pid 3403
STAT uptime 3210
STAT time 1343508734
STAT version 1.4.4
STAT pointer_size 64
STAT rusage_user 0.045993
STAT rusage_system 0.162975
STAT curr_connections 10
STAT total_connections 31
STAT connection_structures 12
STAT cmd_get 4507
STAT cmd_set 1260
STAT cmd_flush 2
STAT get_hits 4491
STAT get_misses 16
STAT delete_misses 2
STAT delete_hits 2
STAT incr_misses 0
STAT incr_hits 0
STAT decr_misses 0
STAT decr_hits 0
STAT cas_misses 0
STAT cas_hits 0
STAT cas_badval 0
STAT auth_cmds 0
STAT auth_errors 0
STAT bytes_read 6144475
STAT bytes_written 21262077
STAT limit_maxbytes 536870912
STAT accepting_conns 1
STAT listen_disabled_num 0
STAT threads 4
STAT conn_yields 0
STAT bytes 147189
STAT curr_items 340
STAT total_items 1260
STAT evictions 0
Here's a recent pingdom test: http://tools.pingdom.com/fpt/#!/zdViZURr3/http://www.kikbo.com/buy

Answer 1

You have to configure prestashop to use memcache in the backoffice. Therefore simply go to the preferences->performance tab and scroll down. Set prestashop to use the cache and select memcache as caching option.
You then have to specify the memcache servers that should be used by prestashop. You should then see an immediate performance increase!
Unfortunately prestashop has some problems with memcache (information not getting refreshed,...). I wrote a blog article about that with some code to fix this: http://www.supnig.com/blog/caching-mysql-results-with-memcached