Unexpected layout _rsc behavior?

[alyustik]

Hey guys!
I've got a section on my site, where I use layout.
I fetch a lot of data in that layout, and almost no data on corresponding to it slug-pages.
But when I navigate from one page of this section to another I see that browser requests both layout and page data merged in a unique _rsc-file on every request, that's a huge overhead in my case.

I did expect that layout rsc will be loaded once and then there will be a small chunks of page-related data. Yet it is different.
Is it correct behavior or I do something wrong?