Request rate to remote schema through hasura engine is very slow

## Bug description

I try to benchmark our server in production environment. I use autocannon for that purpose.
**Case 1**: I will benchmark hasura engine (requests will be sent to hasura engine which will forward theme to remote schema: our API server).
**Case 2**: I will send directly requests to the API server.
The result is very surprised. The request rate in case 1 is hundred times lower than case 2.
I test again in local environment, the result does not change.
As you can see, the latency in case 1 is higher than case 2.

**Case 1:**


**Case 2:**


## How to reproduce
I just create a repository to reproduce this issue:
https://github.com/bkstorm/hasura-engine-benchmark

## Expected behavior
I hope the request rate in two cases are similar.

## Hasura information

## Environment & setup

- OS: Mac OS
- Database: PostgreSQL
- Node.js version: v12.22.1
- Hasura version: v1.3.3