Hi,
a Jar file can be renamed to the extension zip and then manipulated by an archiver/packer tool capable of handling zip archives.
Window XP and Vista can handle such "compressed folders" internally.
You could just remove any unwanted 3rd party library contents and thus repackage your Jabaco classes in a smaller jar.
Rename it back to jar afterwards.

There are numerous "jar stripping" tools available.
They remove unused classes from ja file and take out debugging information.
Currently, I have no recommendation. All tools I tried have had some drawbacks.

Jar files may be "sealed" or "signed" by adding a signature to the Jar MANIFEST.
But this seems not to be the case for Jabaco Jar files.
For Jabaco Applets, the Jar files have to be signed. Otherwise they are not accepted by modern web browsers.

Greetings

A1880

Hi Milan,
yes. You can specify a CLASSPATH which tells the Java virtual machine where to look for libraries.
Look here for details.
But your advantage is limited. The loading time should be fairly the same compared to loading one big library.

When you compile your Jabaco application into an exe file, Jabaco will pack all needed libraries into a self-extracting executable.
This exe creates a temporary jar file whenever you start it. You'll find it under environment path %TMP% (or is it %TEMP%? I can't remember.)

Greetings!

A1880