Async calls seem slow 🐢 

## Description

After conducting some empirical testing, Appier is underperforming regarding async call handling.

Running the same App through FastAPI handles at least 10x-100x more requests than Appier.

## Implementation

Try to find a fix for the issues affecting Appier's async call handling.

**Verify:** there's some timeout kind of waiting going on, it is something to look into.