MySQL Forums :: Performance :: Lag when connecting to DB

Hello everyone,
i don't know if this is the right forum for my problem anyway i try asking.

I have built my own management application for my family's music shops, it runned smoothly for 4 years (with some monthly upgrade) then 2 months ago we upgrade our server (to an Intel xeon quad core(x2) RAM 4GB ECC 1,4 TB HD RAID 5 SUSE 11) I have configured everything in a pretty standard way , but after 55 days up it started to lag on connections only from its LAN i mean from the WAN(internet) the connection time is always the same instead from the LAN of my first shop (the server is in the basement) it takes 10-15 seconds(!!!) to connect , but oddly after connection queries are executed in the standard time (0,1 - 0,02 sec).....
the only thing i have chaged in the net settings is the /etc/hosts.allow and /etc/hosts.deny for the sshd daemon in order to accept connection only from the internal LAN....any ideas????

Thank you