Apngs Playing Slower In Firefox Since Updating To Version 67

I created an APNG yesterday that played fine and just as fast as it should but today, since updating to 67, the same APNG is playing really slowly. I think it might have something to do with one of the changes listed in the release notes, "Painting sooner during page load but less often". Any way I can get the APNG to play faster? Also, at the top of my Firefox Options menu, it says, "Your organisation has disabled the ability to change some options." What does that mean?

 

The APNG plays fine in Chrome but I prefer using Firefox over Chrome and shouldn't Firefox play APNGs better than Chrome anyway? There's been support for them in Firefox much longer than in Chrome.