Bug 7514 - libcairo 1.2.0 much much slower than 1.0.4 on an ssh connection
Summary: libcairo 1.2.0 much much slower than 1.0.4 on an ssh connection
Alias: None
Product: cairo
Classification: Unclassified
Component: xlib backend (show other bugs)
Version: 1.2.0
Hardware: x86 (IA32) Linux (All)
: high blocker
Assignee: Carl Worth
QA Contact: cairo-bugs mailing list
: 7724 (view as bug list)
Depends on:
Reported: 2006-07-13 09:37 UTC by Claudio Sacerdoti Coen
Modified: 2006-08-02 16:44 UTC (History)
1 user (show)

See Also:
i915 platform:
i915 features:


Description Claudio Sacerdoti Coen 2006-07-13 09:37:11 UTC
Upgrading libcairo 1.0.4 to 1.2.0 we noticed that an application of ours,
run over an SSH connection with X forwarding enabled, is between 12 and 15 times
slower (hence unusable).
The application does intensive use of text rendering via gtksourceview and
gtkmathview. Investigating the reason, we realized that every application that
does intensive use of text rendering (e.g. gvim) is much slower too! (just open
with gvim a big file on a slow connection and you will see by yourself).

Comparing network traffic using our application, we noticed that:
 1. the overall size of the exchanged packets with version 1.2.0 is only
    slightly bigger than 1.0.4.
 2. the overall number of exchanged packets with version 1.2.0 is about 6
    times bigger.

We suspect 2 to be a possible cause because of the latency of every packet
during the roundtrip.

Other infos: we are actually running the testing version of Debian. The
phenomenon can be reproduced both on PC with hardware acceleration and on PC
wihtout it.
Comment 1 Behdad Esfahbod 2006-07-15 18:53:46 UTC
Seems like the bug reported here:


Unnecessary Xflush calls are being made with cairo 1.2.  Will be fixed in 1.2.2.
Comment 2 Carl Worth 2006-07-27 00:38:26 UTC
The fix for the XSync bug has now been pushed out into cairo "1.2.1":



Can you please test that that fix does indeed fix the problem you noticed? You
could do this by pulling the latest version of cairo from git, or else by
downloading the patch from the URL quoted above, and applying it.

If we don't hear feedback one way or the other by the time all the other blocker
bugs are fixed, then we'll assume that this bug is fixed and we'll release 1.2.2.


Comment 3 Claudio Sacerdoti Coen 2006-07-27 01:26:36 UTC
Dear Carl,

indeed the patch solves the problem. I think you can close this bug.

Comment 4 Behdad Esfahbod 2006-07-27 08:33:43 UTC
Comment 5 Carl Worth 2006-08-02 16:44:17 UTC
*** Bug 7724 has been marked as a duplicate of this bug. ***

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