Cloud function execution times variance

Hi there,
I am experiencing very different execution times for the same function with the same input data in the cloud. The function code is nothing special, just some creation of documents (50). Is there anybody else experiencing the same issue?

Maybe cold start maybe server load?

Well I am experiencing this for at least two days now, that the same function with the same input data is taking from approx 1s to 30s (times out)

How often after executions?

This is an example of today

So I can not really see a pattern here

It is getting worse today. Out of approx 20 requests there are 9 timeouts (30s), 2 completions > 20s and only 9 in under 5s. Just for reference, all this function does is creating 50 documents. So it should be a fairly easy task from my point of view. Are there any best practices how to create many (even though 50 are not that many) documents?