It would be great if there were some easier way for plugins to execute long background jobs.

Slim::Utils::Scheduler works great it you can divide the background job in small chunks, but this isn't always possible. If you use Slim::Utils::Scheduler if background jobs that take long time it affects music playback and makes the SC/SB user interface unusable during the time.

On Linux I can pretty easy create a separate .pl file and start a separate process for that, but this doesn't work on Windows since perl.exe isn't guaranteed to be installed.

Maybe it would it be possible to provide a bgjob.exe/bgjob.pl with SqueezeCenter which a plugin could launch with parameters. The bgjob.exe/bgjob.pl could then use the parameters to load the necessary plugin classes and execute the specified method. 

I know each plugin could bundle its own bgjob.exe, but it feels like it would be better to provide some standard way for plugins to run background jobs that doesn't cause music playback issues. After all it is also in the interest of SqueezeCenter to behave as good as possible even though some plugins are missbehaving by not dividing its background jobs in millisecond chunks.