Apollo Router request to subgraph

How can I make my apollo router make GET requests to subgraph instead of POST.
Based on my benchmark, GET outperforms POST. But it only happen between client & the router.
I want to improve the network performance by making GET requests from router to subgraph instead of POST.

federation_version: =2.0.1
subgraphs:

  product:
    method: GET
    routing_url: https://localhost:8081
    schema:
      file: ./subgraphs/product.graphql