>> my recollection is that installing ~1200 packages on those systems and 
>> "loading the world" took something like 5 minutes
>
> I'm not sure I understand what you mean here.  Do you mean that 
> byte-compiling and loading ~1200 packages takes about 5 minutes (which 
> would not be a problem per se AFAIU)?  Or that loading ~1200 already 
> byte-compiled packages takes about 5 minutes?  I took the file you 
> posted in bug#61004, modified it a bit to make it work with emacs -Q 
> (without external packages), and on my computer emacs -Q -l loadall.el 
> takes ~4.5 seconds.
>

(Of course I forgot to attach the file.  Here it is.)