Despite the demonstrated usefulness of dynamic taint tracking techniques in mobile privacy security, poor performance attained by prototypes is a big problem. A novel optimization methodology for dynamic taint tracking based on just-in-time compilation is presented. First, the taint propagation logic is separated from the program logic precisely to simplifying the complexity of the taint propagation analysis. Then, a taint propagation framework is proposed and the correctness of the taint propagation analysis is proved..Finally, redundant and inefficient taint propagation codes are transferred to efficient and equivalent codes by adopting the methods of eliminating, replacing and moving. Experimental results show that 38% of memory usage and the time of execution of taint tracking instructions are saved for every single hot trace, and on average the performance of dynamic taint tracking system is improved 6.8%.