"Apache Tomcat enjoys the reputation of being a small but very formidable servlet container capable of handling heavy production loads. Its most common role probably is as the application server for lightweight J2EE applications (servlets, plain old Java objects, and no EJBs). In such a role, it often handles significant production loads, for which these types of lightweight applications are best suited.
"Tomcat's default installation, though, is configured to handle medium loads. Running an application on Tomcat in high-load environments requires further tuning..."