Operating system name and version: CentOS 5.0 (Linux VSIAPP08 2.6.18-194.el5PAE #1 SMP Fri Apr 2 15:37:44 EDT 2010 i686 i686 i386 GNU/Linux)
Version of smsd: 3.1.15
Smsd installed from: sources
Name and model of a modem / phone: wavecom
Interface: USB

I got the following log (/var/log/smsd_test.log) while executing your test scenario (http://smstools3.kekekasvi.com/topic.php?id=548):

sms-file processing in checked folder took longer than expected. It took more than 5 seconds to process 1 file in checked folder.
In my production environment, even took longer than 30 seconds :(

Any idea, whats wrong with my server setup?