[tex-live] TeX performance over the years going downhill

Taco Hoekwater taco at elvenkind.com
Sat Aug 27 10:40:06 CEST 2005

Hi Gerben,

> And I have seen more reports corroborating this. Let me stress: apart 
> from TeX, this system is completely the same. Sometimes people report 
> that their older TeX is about twice as fast as the newer. The big 
> difference seems to have been with some web2c release, probably the one 
> where most binaries were folded into pdfetex.

You should make sure your volunteers do these tests with identical
values for the variable arrays like main_memory.  Recent versions
of (pdf)TeX have much larger (and more, compared to Knuth's TeX)
array sizes, resulting in bigger malloc() arguments, resulting in
more time spent in system, but also in user, for the extra
initialization code (zero-ing 32MB of memory takes 16 times longer
than zero-ing 2MB of memory).

I suspect this is the problem, because ConTeXt has not become
noticeably slower, and ConTeXt has used large arrays all along,
so that would be consistent.

Also, are you sure that the trees are identical? Larger trees
and/or disk-access-enabled trees could account for at least some
of the extra time in user space.

Greetings, Taco

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