Does startup time for Cloudrun docker image delays autoscaling?

Question

I am currently using express.js as the main backend. However, I have found that fastify is generally faster in performance.

But the downside of fastify is that it has a relatively slow startup time.

I am curious that would it slow down the autoscaling of Cloudrun?

I've seen that Cloudrun autoscales when the usage is over 60%.

In this case, I am thinking slow startup time can delay the response while autoscaling which can be a reason not to use fastify. How does this exactly work?