Composing a solution from subregions

Hello everyone; I would like to be able to split my simulation region into parts; solve those partially, combine those to get the solution.
The reason is that the problem is composed of repeating structures and I hope to increase the calculation speed.
Can anyone point to an example; I could not find any.
Thanks in advance

Have a look into this:

and also section 72 ff

Hope this gives some ideas.


Thank you very much; I was not aware of that resource. That should at least keep me busy for some time.