Why is Google Cloud Tasks so slow?

I use Google Cloud Tasks with AppEngine to process tasks, but the tasks wait about 2-3 minutes in the queue before being sent to my App Engine endpoint.

There is no "delay" set on the tasks, and I expect them to be sent right away.

So the question is: Is Cloud Tasks slow?

As you can see is the following screenshot, Cloud Tasks gives an ETA of about 3 mins:

The official word from Google is that this is the best you can expect from their task queues.

In my experience, how you configure tasks seems to influence how quickly they get executed.

It seems that:

• If you don't change the default behavior of your task queues (e.g., maximum concurrent, etc.) and if you don't specify an execution time of a task (e.g., eta) then your tasks will execute very soon after submission.
• If you mess with either of these two things, then Google takes longer to execute your tasks. My guess is that it is the extra overhead of controlling task rate and execution.