Abstract. Runtime monitoring is an effective means to improve the reliability of systems. In recent years, parametric monitoring, which is highly suitable for object-oriented systems, has gained significant traction. Previous work on the performance of parametric runtime monitoring has focused on the performance of monitoring only one specification at a time. A realistic system, however, has numerous properties that need to be monitored simultaneously. This paper introduces scalable techniques to improve the performance of one of the fastest parametric monitoring systems, JavaMOP, in the presence of multiple simultaneous properties, resulting in average runtime overheads that are less than the summation of the overheads of the properties run in isolation. An extensive evaluation shows that these techniques, which were derived following a thorough investigation and analysis of the current bottlenecks in JavaMOP, improve its runtime performance in the presence of multiple properties by up to two times and the memory usage by 34\%.