Performance questions

Incredible work! I was trying to see what kind of overhead there is to call a wasm function from Python.
I am using WSL2 on Windows, with a recent Fedora, CPython3.10.
Re-using the exact [gcd.wat](https://github.com/bytecodealliance/wasmtime-py/blob/main/examples/gcd.wat) from the examples, it looks like any call has a "cost" of about 30μs.

The code I used is a simple timer to compare performance:

```python
import wasmtime.loader
import time
from math import gcd as math_gcd
from gcd import gcd as wasm_gcd

def python_gcd(x, y):
while y:
x, y = y, x % y
return abs(x)

N = 1_000
for gcdf in math_gcd, python_gcd, wasm_gcd:
start_time = time.perf_counter()
for _ in range(N):
g = gcdf(16516842, 154654684)
total_time = time.perf_counter() - start_time
print(f"{total_time / N * 1_000_000:8.3f}μs")
```

This returns about:

```bash
0.152μs # C code from math.gcd
0.752μs # Python code from python_gcd
31.389μs # gcd.wat
```

Note that I tested this with an empty "hello world", and the 30μs are still there.
I am wondering about 2 things:
+ is this overhead inevitable and linked to the design, or are there ways to reduce it?
+ I noticed in the gcd.wat code that input parameters are expected to be i32, but the code does not fail when parameters exceed 2**32, so I was wondering how this works