JavaMail get IMAP folder size very slow

[Tod Stroszer]

I was asked to rewrite this perl code that uses perl's MAIL::IMAPClient API to get the size of an IMAP folder to Java using JavaMail. The perl looks like

        my $size = {};
        my $nmsg = {};
        foreach my $folder (@folders) {
                next if ($folder eq "#user.$username");
                $imap->examine($folder) or next;
                my $hash = $imap->fetch_hash("RFC822.SIZE");
                if ($folder =~ /^"/) {
                        $folder =~ s/^"//;
                        $folder =~ s/"$//;
                }
                $folder =~ s/^#user\.$username\.//;
                $size->{$folder} = 0;
                foreach my $messageid (keys %$hash) {
                        $size->{$folder} += $hash->{$messageid}->{'RFC822.SIZE'};
                }
                $nmsg->{$folder} = scalar keys %$hash;
        }

The perl basically totals the rfc822 size of each message in an IMAP folder to get the total size of the folder. I rewrote this in Java like

            if (folder.getName().length() != 0) { //root folder
                if (folder.getMessageCount() != 0) {
                    long msgs_size = 0;
                    log.info("folder.getMessageCount() " + folder.getMessageCount());
                    folder.open(Folder.READ_ONLY);
                    Message[] messages = folder.getMessages();
                    log.info("messages.length " + messages.length);
                    log.info("msgs_size " + msgs_size);
                    for (int x = 0; x < messages.length; x++) {
                        IMAPMessage tmp = (IMAPMessage) messages[x];
                        if (tmp.getSize() != -1) {
                            log.info("tmp.getSize() " + tmp.getSize());
                            msgs_size = msgs_size + tmp.getSize();
                            log.info("msgs_size " + msgs_size);//size in bytes
                            log.info(msgs_size / (1024L * 1024L)); //converted to MB
                            }
                    }
                }

The perl and java give identical results for IMAP folder sizes - but the Java takes *much* longer to run. For my mailboxes, the perl takes about a minute, while the Java takes about 45 minutes. I'm not sure why this is happening. Is there anything about my code, or any other factors I should be looking at that would explain why Java takes so much longer to do the same thing?