Network can be a big bottle neck and we should not forget, we already took the journey where we had to come up with solutions because we overlooked the network. E.g. on a best case scenario, we would incur a round trip time of 56 ms for data to travel between London and New York. That’s one RTT in fiber on a best case scenario and often we have to incur multiple round trips. Devices can get faster, browsers can get smarter, but network latency will stay as we have a hard physical limit.
Not saying that JS parse/compile time does not deserve similar attention. But, just want to shed light on the fact that overdoing code-splitting can lead us back to problems which we already solved. In the end, most importantly, is like what you mentioned, measure yourself and take actions accordingly.