Bug report

Bug summary

"matplotlib/examples/animation/double_pendulum_sgskip.py": The animation seems to be speed up by either factor 2 or factor 4 (mostly factor 4, the behaviour isn't consistent though). So per second, about 2 or 4 displayed "seconds" are passing in the animation window with the animation processing significantly faster as expected.

Code for reproduction

The example was not changed.

Matplotlib version

• Operating system: Linux version 4.20.3-arch1-1-ARCH (builduser@heftig-25602) (gcc version 8.2.1 20181127 (GCC))Fix autofmt_xdate() when using in conjunction with twinx() #1 SMP PREEMPT Wed Jan 16 22:38:58 UTC 2019

• Matplotlib version: 3.0.2

• Matplotlib backend: TkAgg

• Python version: 3.7.2

• Other libraries: Numpy: 1.16.0
  Scipy: 1.2.0

I installed Python from the Arch repositories. I installed matplotlib via pip.