I use a chrono, they're not all that expensine and are a good indicator of tuning. Gained 20fps sometimes and reduced noise using a chrono to judge the results of work done. There's stuff on your bow reducing speed and when those things don't pull their load equally vibration which reduces speed results. A chrono can indicate a problem and doing different things show the work is having a positive result.
Becareful you don't drill the thing, but more careful when letting friends use it. Friends seem to care less about putting an arrow through one.