We are using Dell 2850 dual 3.2 Xeon processor, 8 Gig of Physical memory and 15rpm SCSI disk for caching (no raid). The software is FC 4 64 bit with Squid 2.5Stable13. Below is the way I complie my Squid: --prefix=/usr --exec-prefix=/usr --bindir=/usr/sbin --libexecdir=/usr/lib/squid --localstatedir=/spool/squid --sysconfdir=/etc/squid --enable-snmp --enable-kill-parent-hack --enable-delay-pools --enable-storeio=aufs,diskd,null --enable-removal-policies=heap,lru --enable-arp-acl With the above compilation and configuration, proxy is doing well. Now I check the number of treads, and found out that it has 4. Can we obtain better performance if we have greater number of treads? Can you please help me to understand the following: --enable-async-io[=N_THREADS] Shorthand for --with-aufs-threads=N_THREADS --with-pthreads --enable-storeio=ufs,aufs --with-aufs-threads=N_THREADS Tune the number of worker threads for the aufs object store. --with-pthreads Use POSIX Threads --with-aio Use POSIX AIO --with-dl Use dynamic linking note that we are using "aufs" on the cache_dir. Thank you very much, Wennie