IMAP extension causing delays

Hello, I need PHP's IMAP extension for my web app but it is really slowing my server up. My setup: Fedora Core 5, Apache 2.2.2, PHP 5.1.4 (run as CGI with suPHP), PHP IMAP extension - all standard FC5 RPMs. The test page is simple - just a call to phpinfo(). Without the IMAP extension, the response time is almost immediate. With the IMAP extension it takes 2-3 seconds to respond - sometimes as much as 4 secs. Watching with 'top', I can see php-cgi is called immediately when the request is received. With the IMAP extension installed, after php-cgi starts, it then drops to the end of the 'top' list, consuming 0% CPU and 2.0% memory. It remains there for the 2-3 second delay before coming into play again an running the script quickly. Without the IMAP extension, it just ends quickly having finished the request. From this, it is clear to me there is some major delay being introduced by the loading of the IMAP extension. Any ideas on how to resolve this? Thanks, Edward