An overview on the implementation of new physical effects into the heterojunction bipolar transistor compact model HICUM/L2 is presented along with a description of the quality testing procedures performed before its public release for production circuit design in commercial simulators. Related topics such as potential measures for model run time improvements and failures are also discussed. Significant differences in run time for different commercial circuit simulators reflect their different approaches towards compact model implementation and solution of the non-linear circuit equation system.