Q:

Drupal 7 is too slow on "first load"

I hope someone can help me with this Drupal 7 issue.  I noticed that loading time is very slow when I enter the site address for the "first time".  It takes about 20 (average) seconds just to start loading files and displaying the content.  Like it has some delay.  However, after that period it's very fast and everything is ok.  Once the page(s) is/are loaded, we can refresh them quickly and without any delay. 
I attach an image to see Chrome's Network Waterfall. 
Thank you all. 
Image: http://i.stack.imgur.com/vuejk.png (take a look at the second row)
[UPDATE] I'm using php-apc but still have the same problem. 

A:

This is (most likely) because of the Drupal Cron tasks that are run every few hours/days (depending on settings).  Drupal then executes all the queued cron jobs.. which can take a long time. 
Have a look at this drupal.stackoverflow page. 
e: Also, this tweak may help, but I haven't tried this myself: http://drupal.org/node/1576686

