Was just writing into this: Is there a way to serve Html and dynamic imports from CDN? - #11 by paulishca. Please take a look at this image.
This is before I put back dynamic imports into static (back into the JS bundle). As I get my main bundle from CDN (AWS Cloudfront), ~800k get to me from Frankfurt (or wherever because of the Cloudfront diversity) to Dubai in 145ms. You can see the speed per various sizes I get from my EBS (with elastic app network balancer) with EC-2 for the split code. This project has no users at the moment, it’s a WIP. In your case, with many users you challenge the infrastructure in multiple points (server memory, server bandwidth, NGINX (or balancer) bandwidth, network interface(s) bandwidth.
I’d delete my local IndexdDB in the browser and have look at the performance in delivery of all those fetches.
