Firefox Mobile (Android) doesn't follow system press-hold delay setting. Potential accessibility barrier for some. I noticed that the context menu would appear slightly faster in Firefox than elsewhere on my smartphone, after a bit of experimenting I came to the conclusion in the title.
While this isn't an issue for me at all as my system set hold delay is very similar that what Firefox's internal default is, however this could be a major issue for persons with certain motor function impairments and thus should be so.