About: http://webisa.webdatacommons.org/318468188

Property	Value
http://www.w3.org/1999/02/22-rdf-syntax-ns#type	http://www.w3.org/ns/prov#Entity
http://www.w3.org/ns/prov#value	I would really have to see an explain plan to know where the slow parts were, as I do not see anything particularly nasty in your code.
http://www.w3.org/ns/prov#wasQuotedFrom	stackoverflow.com