2-second delay when calling sls invoke on a lambda?

When using sls invoke to call a lambda function, there seems to be a delay of 2 second before the function is actually invoked. Since I’m trying to pinpoint a performance issue, this is quite annoying.
Below a sample output of a function that does basically nothing - with the lambda already warmed up.

What is causing this delay? Is there any way to avoid it?

Thanks!

$ time sls invoke --function hello --data “{}”
{
“statusCode”: 200,
“body”: {
“message”: “ok”,
“input”: {}
}
}

real 0m2.331s
user 0m0.966s
sys 0m0.099s