Hi, removing the macros from default group will improve the performance -- actually running alert macros during heuristic is useless ... if you have no alert macro in the start group and default group, the heurstic run will not touch /sapapo/am_alert at all. Please check whether you have other jobs running in parallel.
You can start a ST12 trace with "trace workprocesses" to trace your herustic run when it is running. The trace will tell you what is the bottleneck process during background job run.