Connection Pool Problem

Hi,
       I'am using PostGreSQL version 7.1.3 with Tomcat.
       I have written a connection pool program which takes a parameter from
configuration file and makes a pool of connections out of it. The problem
comes during the making of the initial few (4 - 5) connections which take a
lot of time and then later on the rest of the connections are smoothly made
within a span of a minute.
   Is this an issue with the database, why is it taking so much longer for
the initial few connections to be made with the database ??

Waiting for reply.

regards
Kamal