Java Signed Jar Files - help needed

I am looking for someone to help me with signing Java Applets. I have a project with several Applets running online and they run slowly at the moment, and I feel that having some of the code within a signed jar file will help here.

I need someone with the experience of using Signed Jar Applets to write a script that will generate multiple Jar files and then change each HTML file to access the code from within the Jar file. It is for an educational game, and the jar file would contain code and images (but not audio as that can load in real time).

There are a total of 28 applets in the project. The code needs to run under Windows and also online.