Option to precache multiple requests simultaneously

If I always have to wait for the full installation of the service worker before the page is displayed, why not to tell the service worker that assets can be loaded not sequentially, but as quickly as possible-in parallel?

On a slow connection, we have to wait a very long time for a sequential download, even on http2

My case (slow 3g connection): 13 page assets are loaded in parallel in 5 seconds and then 22 assets are loaded with service worker sequentially for about a minute over http2 (13 of them are the same ones that loaded in 5 seconds for the page and the main size of all assets falls on them)