The LBTS (lower bound time stamp) quarry is key problem for TM (time management) performance. An optimized method will be proposed for improve the TM performance in HLA(high level architecture). It can reduce the frequency of LBTS transfer, and time-constrained federates will be notified LBTS only when LBTS is changed rather than they quarry LBTS actively. Reliable multicast services are applied to reduce the communication cost. These algorithms have been used in TM in self-developed AST-RTI (advanced simulation technology-run time infrastructure), and application systems showed that RTI real time performance has been improved. Then the simulation application problems in RTI TM mechanism and solutions will be discussed.