Heavyduty CPU suckage: procmail pre7 SunOS and large emails

If I get a large email, it seems to cripple the mailhost....

% procmail -v
procmail v3.11pre7 1997/04/28 written and created by Stephen R. van den
Berg                                                       
<srb(_at_)cuci(_dot_)nl>

Locking strategies:     dotlocking, fcntl(), lockf(), flock()
Default rcfile:         $HOME/.procmailrc
Your system mailbox:    /var/spool/mail/luomat

% uname -a
SunOS kira 4.1.4 6 sun4m


procmail just sits there and sucks CPU waiting for a kernel-lock
(according to the verbose log)

Anyone else seen this?

TjL