Query vastly outperforms initial subscription fetch

### Version Information

Server Version: 2.0.7

### Environment

OSS

### What is the expected behaviour?

I expect subscription to return the initial results as fast as queries plus the multiplexing window.

### Keywords

"subscription slower"

### What is the current behaviour?

Our multiplexing window is configured to be the default (1 sec). Yet the response time is multiples of a subscription vs its sister query is in the multiple of seconds.

### How to reproduce the issue?

I don't have an exact reproduction, as you can see in the video, the query is fairly simple. We do have a fair bit of complexity in our permission system. I also realized that we are using SQL views there for reducing repetition in our permission system which could kill some optimization Hasura does, in terms of combining permission-checks with relation joins. But that should not be the core of the issue here, I assume, because the sister query is still fast enough.

### Screenshots or Screencast

https://user-images.githubusercontent.com/4051932/134877170-57c89588-5041-4407-b38b-13a131986177.mov

### If the bug is confirmed, would you be willing to submit a PR?

I could try, have not written serious Haskell yet but there is no time like now to learn it