With this squid configuration: acl localnet src 172.16.0.0/12 acl localnet src 192.168.0.0/16 acl SSL_ports port 443 acl SSL_ports port 85 acl SSL_ports port 81 acl SSL_ports port 5443 acl Safe_ports port 80 acl Safe_ports port 21 acl Safe_ports port 443 acl Safe_ports port 70 acl Safe_ports port 210 acl Safe_ports port 1025-65535 acl Safe_ports port 280 acl Safe_ports port 488 acl Safe_ports port 591 acl Safe_ports port 777 acl Safe_ports port 5443 acl Safe_ports port 85 acl Safe_ports port 81 acl CONNECT method CONNECT http_access allow manager localhost http_access deny manager http_access deny !Safe_ports http_access deny CONNECT !SSL_ports http_access allow localnet http_access allow localhost http_access deny all http_port 3128 hierarchy_stoplist cgi-bin ? cache_dir ufs /var/spool/squid 1000 16 256 max-size=999000 cache_mem 512 MB maximum_object_size 4096 KB memory_pools off cache_swap_low 90 cache_swap_high 95 dns_nameservers 172.16.1.1 client_db off half_closed_clients off max_filedesc 4096 coredump_dir /var/spool/squid refresh_pattern ^ftp: 1440 20% 10080 refresh_pattern ^gopher: 1440 0% 1440 refresh_pattern -i (/cgi-bin/|\?) 0 0% 0 refresh_pattern . 0 20% 4320 acl users src 172.31.0.0/16 delay_pools 1 delay_class 1 2 delay_parameters 1 5000000/10000000 5000000/10000000 delay_access 1 allow users squid very often load CPU at near 100%, with cca 200 users and 4000 connections (~2000 to users, 2000 to internet). Removing delay pool configuration has no big effect. HW configuration: Dual core E8500@3.16GHz CPU, 4GB RAM, 2x SATA 7k2 Raid Edition disks in SW RAID1 for squid cache (disk performance seems isn't problem, IOWAIT is small), gigabit ethernet cards to internet (~800 Mbps line) and to LAN. It is squid-3.2.3.20121106.r11695-1.fc14.i686 on Fedora 14 i686 (I test it with some older squid 3.1 version and same configuration too, but results were same, or rather worse) It this CPU load normal, or can be there done some performance tunnning for it? Thanks in advance, Fr. Hanzlik