Severe lag in LibreOffice Draw due to /etc/X11/Xsession.d/90atk-adaptor

[Roland65]

On Ubuntu 16.04, I found that LibreOffice Draw (4.2.x, 5.0.x, 5.1.x versions) was extremely slow when selecting and moving a bunch of shapes in some relatively simple drawings. This occurred on five Ubuntu boxes I have. However, there was no slow down on Windows with the same files and also on a fresh install of Xubuntu 16.04 in a virtual machine.

After a long investigation, I finally found the culprit: for some reason, the package gnome-orca was installed on my machines and this package pulls down the libatk-adaptor package, which in turn installs the file /etc/X11/Xsession.d/90atk-adaptor.

I found that removing that file solves the problem and now LibreOffice Draw is fully responsive. Perhaps other graphic applications could suffer from the same problem, but I was not able to see some huge lag as in LO Draw.

To reproduce:
1. install libatk-adaptor (version 2.18.1-2ubuntu1:amd64 of Ubuntu 16.04) or simply the gnome-orca package

2. open the attached file test.odg with LibreOffice Draw, and select a bunch of shapes (for example, the two axes and shapes of the page bottom). Then, try to move the selected shapes with the keyboard (shift + arrow) and you should see a severe lag. If you maintain the key pressed during the move, then the UI is blocked during some time. Moving the shapes using the mouse is faster but still quite slow as compared to the expected performance.

3. remove the file /etc/X11/Xsession.d/90atk-adaptor and restart X

4. open again the test.odg file. Now, moving a bunch of shapes using the keyboard (or the mouse) is very smooth and fluid, as it should be.

This is 100% reproducible on all the machines I have where the libatk-adaptor package is installed.

[Launchpad Janitor (janitor)]

Status changed to 'Confirmed' because the bug affects multiple users.