API takes longer to load first time opening my webpage

Question

I have a Django app configured on AWS Lambda with zappa.
In this app I created some basic APIs with DRF.

On the otherside I have a ReactJS frontend that makes these GET requests to load in my data.

On my frontend I make a call to get my ID's based on some condition, with this response I get max. 30 ID's where I loop through and make another call for every ID to get their data.

The first time I do this, my api to get the ID's loads perfectly and fast enough, but then when it loops, some api's to get the data goes really fast and some just takes around 10-20 seconds to load.

this only happens the FIRST time I load my page, after that, if I refresh my page, it is up and running in under 1s.

I did some research and I know that AWS Lambda is serverless and shuts down when no one is using the application, so with that in mind, I thought this was why its always slower the first time.

But then I found a setting on zappa "keep_warm" to keep my server running, I also made sure that "keep_warm_expression" is set to 1minute so I thought that my server will keep running.

Yet I still have this problem.

I don't except a fully answer for this as I didn't give any information of my configuration. But because I can't really figure out if this problem is Backend, Frontend or AWS related, I'd just like some tips on where to look or how to figure this out.

Thanks in advance