A major change to the internal workings of Firefox should result in faster web page rendering on most Windows computers. Unfortunately, that doesn’t include Windows XP: starting with version 53.0, Firefox no longer supports XP or Vista.
Firefox 53.0 also fixes at least twenty-nine security issues, so it’s a good idea to update it as soon as possible. Firefox can be rather sluggish about updating itself, but you can usually trigger an update by clicking the menu icon at the top right (three horizontal lines), then the little question mark icon, then
Also in the new release are some improvements to Firefox’s user interface, including two new ‘compact’ themes that free up some screen space. Site permission prompts are now somewhat easier to understand and more difficult to miss. Tab titles that are too long to fit in a tab now fade out at the end instead of being cut off and replaced by ellipses, which makes more of the truncated title visible.