slow performance with lots of spans and anchors in pre?

[dmalan]

In follow-up to #483, we've encountered a similar performance issue with inputs like https://gist.github.com/dmalan/22e14a769a78739dd22de7104ba46bfd, whereby quite a few span and a are inside of pre, as might happen when rendering source code. (To simplify the gist, we've removed all CSS and replaced chunks of code with just foo.) For instance, in an Ubuntu 14.04 Docker container on a Mac Pro, rendering those 399 lines takes 1m13s:

# pip show weasyprint
Name: WeasyPrint
Version: 0.41
Summary: WeasyPrint converts web documents to PDF.
Home-page: http://weasyprint.org/
Author: Simon Sapin
Author-email: simon.sapin@kozea.fr
License: BSD
Location: /opt/pyenv/versions/3.6.0/lib/python3.6/site-packages
Requires: html5lib, pdfrw, Pyphen, cssselect2, CairoSVG, cffi, cairocffi, tinycss2

# time weasyprint test.html test.pdf
/opt/pyenv/versions/3.6.0/lib/python3.6/site-packages/weasyprint/text.py:29: UserWarning: There are known rendering problems with Cairo <= 1.14.0
  warnings.warn('There are known rendering problems with Cairo <= 1.14.0')
/opt/pyenv/versions/3.6.0/lib/python3.6/site-packages/weasyprint/fonts.py:43: UserWarning: @font-face support needs Pango >= 1.38
  warnings.warn('@font-face support needs Pango >= 1.38')

real	1m13.438s
user	1m13.240s
sys	0m0.130s

Any chance there's another hot spot that 46da8b5 didn't already redress?

Many thanks!

[liZe]

rendering those 399 lines takes 1m13s

Shame! Shame! Shame!

Any chance there's another hot spot that 46da8b5 didn't already redress?

I hope so, I'll take a look as soon as possible.

[dmalan]

Thank you kindly!

[liZe]

I have to check twice that I didn't break anything, but that's a major improvement when there are many inlines and lots of lines in a block. Moreover, 0.42 fixes #163, this page should be perfectly rendered now.

[dmalan]

Amazing, thanks so much.

[dmalan]

Albeit on a different machine at the moment, down to

real	0m2.039s
user	0m1.830s
sys	0m0.090s

for the same input now. Thank you, @liZe!