In most cases we recomend using the mod_proxy /apache combination as a frontend to tomcat. However for those looking to squeeze extra performance out of a bare tomcat installation the following may be useful

Apache Portable Runtime (APR) and Tomcat

Per http://apr.apache.org/ Tomcat can use the Apache Portable Runtime to provide superior scalability, performance, and better integration with native server technologies.

Installing the JNI wrappers for APR used by Tomcat (libtcnative)

You can now grab the latest tcnative wrapper from http://tomcat.apache.org/native-doc/ and drop that into the tomcat libs folder (eg /usr/local/tomcat/libs).

We recommend you use the package install methods shown on the above link to obtain the libraries noted. Those should be available using either yum or apt-get depending on your installed distribution.

You should be able to just grab the jar file and drop that into the tomcat libs folder (check in case it is already present).

Remeber to restart tomcat to make that load the updated/new libraries. And check in the tomcat logs to confirm they have been imported correctly.