Performance penalty when using regular expressions in server_name?

[itpp2012]

A different way would to use Lua and an alias table, for a dynamic site I
use this to allow a site multiple aliases all directing to the same root,
its a simple array with 2 lines for each main site, 1 as server_name and
line 2 endless aliases. Its fast and no need to edit nginx.conf just edit a
plain ascii file.

Posted at Nginx Forum: http://forum.nginx.org/read.php?2,246970,246973#msg-246973