By default, Function Compute runs functions on on-demand instances. When no requests arrive for usually 3–5 minutes, the instance is released. The next invocation must initialize a new instance before executing — this is a cold start. Functions invoked sporadically encounter a cold start on nearly every invocation.
How cold start works
When Function Compute receives an invocation on a new instance, it must initialize the instance before running your handler. Once initialization is complete, your handler runs and the instance stays warm. Subsequent invocations reuse the same instance and skip initialization entirely — this is a warm start, which is significantly faster.
Functions under steady traffic warm-start on almost every call. Functions invoked sporadically cold-start on almost every call.