1. A computer-implemented method comprising: receiving an invocation of an invoked interface associated with a class; identifying, based on said class, a plurality of interface lookup artefacts and a cached interface lookup artefact; comparing said invoked interface with a cache interface, said cache interface being associated with said cached interface artefact; responsive to said invoked interface matching said cache interface, returning said cached interface artefact; responsive to said invoked interface not matching said cache interface: searching said plurality of interface lookup artefacts until finding a matching interface lookup artefact, said matching interface lookup artefact being associated with a matching interface that matches said invoked interface, and responsive to finding said matching interface lookup artefact, returning said matching interface lookup artefact and updating said cached interface lookup artefact to said matching interface lookup artefact, and initializing said cached interface lookup artefact to a null value wherein comparing said invoked interface with a cache interface comprises testing whether said cached interface lookup artefact is equal to said null value.