How to make a standalone lift application? Which tools/libraries to use? How does the performance compare to using lift application as a war in some application server?
With onejar maven plugin http://onejar-maven-plugin.googlecode.com/svn/mavensite/usage.html and maven I could package jetty and project with dependencies inside one jar.
The part of the question on performance doesn't really fit with the rest. You are primarily asking how to package the Lift application as a single JAR/WAR. This doesn't have anything to do with the runtime.
At runtime you will still be running inside a Servlet container (could be Jetty, Tomcat or a full-blown JEE server). How you package your application won't affect the performance.
You could take a look at Hudson (a great Continuous Integration Server) to see how they deliver as a single WAR file that contains an embedded Servlet container. You can download the WAR file and run it from the command line: java -jar hudson.war