[Libreoffice-bugs] [Bug 130424] New: Multiple selections cause huge CPU load and heavily delay UI markup

[bugzilla-daemon at bugs.documentfoundation.org]

https://bugs.documentfoundation.org/show_bug.cgi?id=130424

            Bug ID: 130424
           Summary: Multiple selections cause huge CPU load and heavily
                    delay UI markup
           Product: LibreOffice
           Version: 6.4.0.3 release
          Hardware: All
                OS: Linux (All)
            Status: UNCONFIRMED
          Severity: normal
          Priority: medium
         Component: Calc
          Assignee: libreoffice-bugs at lists.freedesktop.org
          Reporter: frank.bruetting at gmail.com

Description:
When you hold down the Ctrl key and then select a few cell blocks with the
mouse in my attached table, the UI gets delayed pretty quick and the CPU gets
loaded pretty much. To my experience, every additional block causes exponential
lags, so selecting 6 blocks causes way more load than selecting 5 blocks (guess
this one additional block doubles the delay time).

I tested LibreOffice 6.3 and 6.4 on both Fedora 28 (X11) and Fedora 31
(Wayland).

I will attach a screen cast and that example document. That document basically
is just a table I copied from a macro-generated XLSX document to this ODT file
(and I applied some sort and color operation on it). With the empty default
table, this is not reproducible.

Steps to Reproduce:
1. Open my attached table
2. Hold the Ctrl key and select a few block with the mouse

Actual Results:
After some selections, the UI gets delayed and there’s a heavy CPU load.

Expected Results:
These selections should not load or delay anything.


Reproducible: Always


User Profile Reset: No


OpenGL enabled: Yes

Additional Info:
• LO options (LO ⇒ View) show that hardware acceleration and anti-aliasing is
checked.
• When I check nothing or only check hardware acceleration, everything works
fine.
• When I only check anti-aliasing, I experience slight lags.

• So the combination of these two options seem to cause this, I guess?



OpenGL vendor string: Intel Open Source Technology Center
OpenGL renderer string: Mesa DRI Intel(R) Haswell Mobile 
OpenGL core profile version string: 4.5 (Core Profile) Mesa 18.0.5
OpenGL core profile shading language version string: 4.50
OpenGL core profile context flags: (none)
OpenGL core profile profile mask: core profile
OpenGL core profile extensions:
OpenGL version string: 3.0 Mesa 18.0.5
OpenGL shading language version string: 1.30
OpenGL context flags: (none)
OpenGL extensions:
OpenGL ES profile version string: OpenGL ES 3.1 Mesa 18.0.5
OpenGL ES profile shading language version string: OpenGL ES GLSL ES 3.10
OpenGL ES profile extensions:

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