Are you following the directions taken by CBM for the OS?
Had CBM directions? There were probably multiple plans by multiple persons.... RTG was a plan, but it didn't went quite far. Instead, external developments became popular. Will any of that go into the kickstart? I don't know, but not too soon because that is a lot of work.
any performances improvements in the pipe?
Not much. Dos buffered I/O should have improved a lot (FRead,FWrite), and it is used by the icon.library, so there are possibly some performance improvements in that respect. Whether it is measurable i do not know. Dos is the next dragon I'm slaying (after graphics), refactoring System-Startup out of dos was one of the results, also writing shells became simpler (we had like 3 methods how a shell could be launched before, see "shell internals" on aminet. It's down to one now).
I guess that since the 89/90 better algorithms exist that can be applied a bit like what you’ve done with intuition but I think also about gfx lib and exec.
Exec doesn't have much. There are memory pools that could benefit from improvement. Unfortunately, there are programs that expect exactly the layout they have today, so no chance. There could be a memory scratch list for small allocations, but as graphics became smarter, memory fragmentation lowered as well, so the problem is not as high as it used to be. There is nothing major for graphics in the pipeline. Maybe some improvements are coming for intuition, but this is still too early to say what else goes into it. The problem is that we cannot really make too much dependent on intuition as CGfx is entangled with intuition V40 in an unfortunate way.