Ive got IPFire running on a RPi B+ and I wondered if it would be worth moving the Squid cache and logs over to a fast USB drive? I've currently got a class 4 SD card so wondered if using an 8 or 10 would also help.
in a user heavy environment a hard drive would be faster than a flash drive because of throughput. For logs putting it on a seperate drive other than the cache would make it a bit faster.
On my device I write the squid logs /tmp/logs which is RAM based. I then used logrotate every hour to copy of them off to a flash drive. This seems to work well.