[XeTeX] Performance [was: Some fontspec details]

[Jonathan Kew]

On 2 Dec 2004, at 10:13 am, Adam Lindsay wrote:

> Jonathan Kew said this at Thu, 2 Dec 2004 09:33:07 +0000:
>
>> Currently,
>> Quartz-based PDF generation is the worst bottleneck; if you run xetex
>> -no-pdf you'll find that the actual formatting process isn't so bad.
>> It's xdv2pdf that really drags things down. I've done some profiling,
>> which indicates that an awful lot of the time is spent on low-level
>> glyph access within the PDF-generating backend of Quartz. :(
>
> Yeah, xdv2pdf being the bottleneck has been crystal clear to me ever
> since making texexec run with -no-pdf  and having xdv2pdf on the final
> run automatically. It's quite quick, and then there can be 5-10 secs
> before the final output is ready.
>
> It doesn't bother me, though, cos xdv2pdf is doing some real *work*, ya
> know, man? That's the stuff that makes it all pretty.

Yes, it's doing work, but from what the profiler shows, I am convinced 
it's doing it inefficiently!

> What does concern me is the occasional infinite loop that XeTeX spins
> into. I presume this is from failing to find a break in a word for an
> overfull box? Does anything else set it off? Has anyone had success in
> staving it off?

That concerns me too; can you provide a small example that shows the 
problem? Preferably without requiring me to get ConTeXt going.... I've 
never tried that.

In a quick test, I find that I can get "TeX capacity exceeded [main 
memory]" if I provide a sufficiently outrageous unbreakable piece of 
text, but I haven't seen an infinite loop....

JK