This plugin creates an entry on the plugin menu which can be used to disable the animated signs on the current map.
Select "Disable Animated Signs" from the Plugins menu when playing a track to stop the animations on all the signs on the map.
To have animations disabled automatically, enable "Automatically disable sign animation" in the settings.
This plugin is open sourced on github. Write up a github issue or open a pull request if you have a proposal for a feature to add.