pcl::precompile-random-code-segments

[chungl@postgres.Berkeley.EDU (Chung Liu)]

In notes.text of the May Day PCL, it says:

>  * You probably also want to begin using a precom file for your system.
>  Do this by having a file whose only contents is
>
>    (pcl::precompile-random-code-segments <your-system-name>)
>
> don't quote <your-system-name>
>
> for example, for the clim system, the precom file has the one line:
>
>   (pcl::precompile-random-code-segments clim)
>
> compile this file after loading and running your system for a while.
> load it before loading and running your system for a while.
> load it before loading your compiled system.  A future version of this
> feature won't require you to have run your system for a while, it will
> only require that you have loaded it.

Could someone explain to me what this precom file does?
I couldn't quite understand it from the notes.
Does it improve the performance of PCL?
Also, what does "loading and running your system for a while" mean?

Thanks in advance.

Chung Liu
(chungl@postgres.berkeley.edu)