[XeTeX] startup time

[Michael Maxwell]

On 7/3/2020 2:28 PM, Zdenek Wagner wrote:
> There are several options:
> 
> 1. Dump your own format with your styles. You will have to regenerate 
> the format after update of any of these style files and you will have to 
> take care of dependencies
> 
> 2. Install TeX on a fast disk such as SSD
> 
> 3. Increase your RAM and use larger disk cache, on my Linux computers 
> the unchanged files can remain in cache for hours

I already have 2 and 3, although afaict 3 has little if any effect, 
because the processing time appears to be taken up with macro expansion 
(or whatever it is that tex does while processing the preamble).

1 is what I was looking for, but how do you do it?  I tried
    xelatex -ini <my tex file>
but it chokes on the \documentclass; or when I try it on my style sheet 
alone, it chokes on the \ProvidesPackage.  Apparently it works with 
plain TeX, but not with LaTeX?  And I'm not sure this would do what I 
want anyway; what it means to "be xeinitix"; a web search for that term 
was unproductive (unless you're looking for some kind of gas warning light).

Can you give me a lead on how to do #1?