When using Shall Belt configuration: https://mods.factorio.com/mod/SchallBeltConfiguration
the speed of the linked belts in this mod do not match the configured speeds.

I have made a post over there about this (cause I think it's probably an update needed in that mod):
https://mods.factorio.com/mod/SchallBeltConfiguration/discussion/64d64ab0ecda64d11dfb090d

But in over a week hadn't even gotten a response.

So now I'm posting this in the hope there could be a fix on this end of the issue.

The main issue is that the linked belts keep the vanilla speeds regardless of what the belts were set to.
So when vanilla is [1] 15items/s [2] 30items/s [3] 45items/s and the config is
[2] 30items/s [4] 60items/s [8] 120items/s.

The linked belts maintain the vanilla speeds and thus drastically slowing down factory throughput.

Any idea's for fixing in some compatibility?

After some digging around, i think i found the problem. This mod creates new prototypes of linked-belt though deep copy of data.raw of parent prototype. However, the problem is that this mod is loaded before Shall Belt configuration, so any value changes to data.raw will not be reflected on the linked-belt prototype created by this mod.

I suspect that this problem should be fixed after adding Shall Belt configuration as an optional dependency.

I got it to work.
In info.json, under dependencies, add , "(?) SchallBeltConfiguration" to the end of the array.

It should fix the problem.

Thanks for the digging.
In the mean time I did tried out a different (similar) mod for the belt speeds and although better, was somewhat suffering from the same condition.

Can confirm that adding the optional dependency did entirely fix the problem.

So I can suggest the following optional dependencies here:
, "(?) SchallBeltConfiguration" (for Shall Belt Configuration)
, "(?) Speeds_and_feeds" (for the Speeds and Feeds mod: https://mods.factorio.com/mod/Speeds_and_feeds )

So that means the problem can be considered [Solved].
It just needs an official update now.