title: time.time() or time.perf_counter() — which is faster?
body: <p>Context: I'm implementing a memory cache with TTLs in my Python project, and it has to withstand considerable throughput. To determine when a cache record goes stale, I save it with a timestamp, and when I retrieve it later I check this timestamp against the current time. If the difference is above the threshold, the record is stale and should be discarded.</p>
  <p>Question: <code>time.time()</code> or <code>time.perf_counter()</code> — which function returns its value faster? Is the difference considerable or negligible?</p>