squid-2.7.STABLE8 delay_pools speed limiting

[root@gw ~]# squid -v
Squid Cache: Version 2.7.STABLE8
configure options: '--bindir=/usr/local/sbin' '--sbindir=/usr/local/sbin' '--datadir=/usr/local/etc/squid' '--libexecdir=/usr/local/libexec/squid' '--localstatedir=/usr/local/squid' '--sysconfdir=/usr/local/etc/squid' '--enable-removal-policies=lru heap' '--disable-linux-netfilter' '--disable-linux-tproxy' '--disable-epoll' '--enable-auth=basic digest negotiate ntlm' '--enable-basic-auth-helpers=DB NCSA PAM MSNT SMB' '--enable-digest-auth-helpers=password' '--enable-external-acl-helpers=ip_user session unix_group wbinfo_group' '--enable-ntlm-auth-helpers=SMB' '--enable-storeio=ufs diskd null' '--enable-delay-pools' '--enable-snmp' '--enable-pf-transparent' '--enable-err-languages=Armenian Azerbaijani Bulgarian Catalan Czech Danish Dutch English Estonian Finnish French German Greek Hebrew Hungarian Italian Japanese Korean Lithuanian Polish Portuguese Romanian Russian-1251 Russian-koi8-r Serbian Simplify_Chinese Slovak Spanish Swedish Traditional_Chinese Turkish Ukrainian-1251 Ukrainian-koi8-u Ukrainian-utf8' '--enable-default-err-language=English' '--prefix=/usr/local' '--mandir=/usr/local/man' '--infodir=/usr/local/info/' '--build=i386-portbld-freebsd8.0' 'build_alias=i386-portbld-freebsd8.0' 'CC=cc' 'CFLAGS=-O2 -fno-strict-aliasing -pipe -march=pentium4 -mtune=pentium4 -march=pentium4' 'LDFLAGS=' 'CPPFLAGS='

squid.conf:
acl limited_speed src 10.20.5.0/24
http_access allow limited_speed
delay_pools 1
delay_class 1 1
delay_access 1 allow limited_speed
delay_access 1 deny all
delay_parameters 1 40960/40960