Jerky scrolling in IE & Firefox: Chrome is fine.

I just set up our scrolling message, and have been very happy with this plugin.

But I started getting complaints from users saying it was hard to read the marquee due to the jerking motion. That confused me, since it scrolls nice and smoothly on my machine. The I loaded our site in Firefox and IE, and sure enough: the message is very jerky and difficult to read.

Is there anything I can do to smooth it out? Or does the author need to make the plugin IE and Firefox compatible? We’re using the latest version of the plugnin (8.3).

https://wordpress.org/plugins/horizontal-scrolling-announcement/