[CentOS] resource efficient log scanning tools

I'm looking for a logfile scanner that can search for regular
expressions in logfiles and send immediate email notifications.  I'd
like to try to find something that doesn't use huge amounts of memory. 
I'm currently running fail2ban and used it to do some of this scanning,
but I'm finding that it can suck up memory and CPU resources when there
is a lot of logging going on.

I am aware of swatch,  but most people say that it is pretty resource
intensive as well.  I came across logsurfer in google search and was
wondering if anyone has experience with it or what other good
alternatives might exist.

While fancy features are nice, I'm willing to forgo them for lower
resource consumption.

Thanks,
Nataraj