It seems that the URL I posted, doesn't do the same as the "real" URL that we were using. I had modified that URL so there wouldn't be any customer-specific references, resulting in an URL that didn't crash our servers. This is the original URL, that *does* crash the servers:
http://servername/clients/clientname/ab-intranet.nsf/v1401WWA2HP?SearchView&Query=([Maatschappij_S]=ACHMEA-Schadeverzekeringen-xvolmachtx)AND(([Library_CategorySelection]=Formulieren)OR([Library_CategorySelection]=Afdrukken%20S.A.F.))&SearchFuzzy=True&SearchMax=1000
We tested this on a 6.5 server, which promptly crashed. Strangely, however, our 6.03 server didn't crash anymore. Weird stuff!