Cache invalidation is affected by the number of AQ threads allocated to the Sponger. It also affects the number of concurrent tasked handled by a Sponger instance.
There is a
AsyncQueue? = 1/0 in the SPARQL section of the virtuoso ini file.
This is obsolete.
Infact the AQ only is used to protect cache from bad data
# virtuoso.ini ... [SPARQL] ... AsyncQueue = 1 ...