The official vIDE page at PUBWorking with precompiled modules

Use of precompiled modules is a powerful feature of vIDE that allows you to reuse your Verilog code without the overhead of re-parsing the sources.

Each precompiled module is stored inside a file with the same name as the module's identifier and with the extension ".vo". The interpreter expects to find such files inside the current directory or in one of those given with the "-o" option (inside the IDE you can use the Preferences dialog box to add custom directories).

Using precompiled modules

They're stored in the vIDE standard library directory (called objects), or in the directory given using either the -Dvide.libdir command-line JVM property, or the Library directory option in the Preferences dialog box. So, as you presume, there's nothing special to do in order to take advantage of them. This is due to the module name resolving mechanism (inspired from the Java Class Loader :). The module finding algorithm works in two steps: first, a module cache is searched for a matching module for the given name. If it isn't found, then a file with the same name as the module and the extension ".vo" is searched inside some known directories. If the file is found, it is assumed to contain the compiled form of the required module, and thus loaded into the cache.

Creating the precompiled modules

Step one

After you finished writing&testing your modules, add one (or more) $export directives with the following syntax:
$export( <exported_module_identifier> * );

This directive can be placed anywhere in the source but outside any moduleor primitive construct; also, for documentation purposes it is recommended to put them at the top of the Verilog source file that contains the modules.

Step two

Run the command line interpreter with the -l option. This will cause object files to be created inside the current working directory. You can move now the object files into a personal library directory or in the vIDE standard library directory.