CREATE INDEX as bottleneck

Hello,

in the last years, we have successfully manage to cope with our data
growth
using partitioning and splitting large aggregation tasks on multiple
threads.
The partitioning is done logically by our applicationn server, thus
avoiding trigger overhead.

There are a few places in our data flow where we have to wait for index
creation before being able to distribute the process on multiple threads
again.

With the expected growth, create index will probably become a severe
bottleneck for us.

Is there any chance to see major improvement on it in a middle future ?
I guess the question is naive, but why can't posgres use multiple
threads for large sort operation ?

best regards,

Marc Mamin