#pragma D option quiet
dtrace:::BEGIN
{
    rate = 0;
}
profile:::tick-1sec
{
    printf("%d/sec\n", rate);
    rate = 0;
}
pid$target:XUL:*SharedMemoryBasic*Create*:entry
{
    rate++;
} 
You can run this script with following command:
$ dtrace -s $SCRIPT_NAME -p $PIDI'd be interested in knowing if anyone else has a similar technique for OSs that don't have dtrace.
