500 Internal Server Error - high amount of nodes

Hallo,

I'm using your module on different sites. Mostly it works like a charm, but on sites with a high amount of nodes (>20.000) it breaks while rebuilding with

Ein AJAX-HTTP-Fehler ist aufgetreten.
HTTP-Rückgabe-Code: 500
Im Folgenden finden Sie Debugging-Informationen.
Pfad: /batch?id=2994&op=do_nojs&op=do
Statustext: Internal Server Error
Antworttext:
500 Internal Server Error
Internal Server Error
The server encountered an internal error or
misconfiguration and was unable to complete
your request.

Right now I haven't took a deeper look. Do you think theres another problem and it's not the amount of nodes, or should be the batch splittet in more parts?

Thanks in advance.

Cheers,
Matthias