Code runs slower in Autopilot cluster compared to GCE instance

I've been doing some benchmarking of difference HTTP request libraries across Go and Rust and I've noticed that the Rust code is running much slower in a Pod in an Autopilot cluster compared to when it is run on a GCE instance (such as a g1-small). The code downloads from a bucket in the same region at about 210MiB/s on the g1-small - but on the Autopilot pod (where the machine-family is n1) it runs at about 100MiB/s. Weirdly this only affects the Rust code - Go for example will download at about 200MiB/s regardless of whether it is a GCE instance of a GKE pod.

I've created a repo that I've been using for reproducing the issue: https://github.com/bennetthardwick/http-download-testing. If anyone has any ideas on investigating this I would appreciate it a lot.