Tuning is something that is very much hands-on and often requires a good deal of fine tuning, both of which are outside the scope of this forum.
As I said previously, you’ll always need to read X GB from the file one way or another. Either it’s slightly more front-loaded or it’s more evenly spread but it’ll be the same amount of data either way.
If you want to graph the network traffic on OSMC, in order to get a better feel for what’s happening with various settings, take a look at this post.