Snort is an IPS and you don’t have it installed.
I guess the performance problems are related to the PPPoE implementation.
As you know, I’m not an expert. Reading what I found on the net, I’m not sure if we can use a better/faster implementation (or maybe we’re already using it).
It seems that you could try adding the following line to /etc/sysconfig/network-scripts/ifcfg-pp0 and then restart the connection with service network restart:
LINUX_PLUGIN=/usr/lib64/pppd/2.4.5/rp-pppoe.so