Nginx (static content + page caching) and Jetty make a good pair on a virtual server. H2 is a fast and lightweight database server and can also go on the same VS. I've had no problems with this technology stack at all - it should be fine until you get such a load that you can afford to upgrade your server setup.

My personal bias is to stay away from frameworks and use JDBC and a text templating library.

I would also stay away from most frameworks. Both the Play and Wicket groups have posts from people wondering where their memory has gone to.