Rated 3 out of 5 stars
I've been using IE View for years, and really like its simple functionality. Unfortunately, it doesn't support MultiProcess, and according to Mozilla's developer blog, extensions using old methods that don't support MultiProcess won't be loaded in Firefox starting in version 57.
For now, this means you can't have this extension enabled and have Firefox use MultiProcess features. Soon, it'll probably mean this extension will not work at all.