Auto-complete very slow for make command, even using auto-complete code from master branch

Hello,

I'm trying to use make command in the OpenWrt repository, but I can't 
type anything after make<space>.
It seems to trigger the auto-complete but OpenWrt has a very big and 
complex Makefile, with a lot of Makefiles across the repository.
I tried to use the _make completion script from the master branch, since 
there is a commit from 2023 that adapts to use with make 4.4, the 
version I'm using it.
Any way to debug that to find the culprit?
I loaded the function with make <tab> and after that `whence -v _make` 
showed that the function I'm using is the newer one.

I'm available to do any tests.

Thanks.
-- 
Marcos Alano