faster equivalent of gettimeofday

In trying to build a very latency sensitive application, that needs to send 100s of messages a seconds, each message having the time field, we wanted to consider optimizing gettimeofday. Out first thought was rdtsc based optimization. Any thoughts ? Any other pointers ? Required accurancy of the time value returned is in milliseconds, but it isn't a big deal if the value is occasionally out of sync with the receiver for 1-2 milliseconds. Trying to do better than the 62 nanoseconds gettimeofday takes