It looks like the JSF Deployer can cause slow startup if many different JSF applications are deployed. In my testing, it adds about 3 seconds for each JSF deployment. My tests are not conclusive, but I'm guessing that since JSF is now loaded by the WAR's classloader instead of Tomcat's classloader then the JSF classes have to be reloaded for each JSF app. I suspect that this causes extra memory usage as well over the old way of doing it.
The solution is to allow all WARs that use the same JSF configuration to share the same classloader for those classes.
I suspect that other deployers such as the Weld deployer and Seam deployer have the same issue. This would be a problem for any deployer that adds jars to the deloyment classpath on the fly.