Removing old (irrelevant) html from pages

Anybody old enough to remember Microsoft FrontPage? So my site spans back over 20 years. Originally designed in FrontPage and it ranked extremely well for about any page I created. My site is an eCommerce site and has grown significantly over time. Currently have about 20K products and well over 1000 categories. Not to mention a bunch of random pages. I have been through a handful of shopping carts over the years. Since ranking has always been good, old html was copied over to the new site each time. Some changes were made here in there but almost every category had some leftover FrontPage code in there. While it wasn't causing any issues, it was really just irrelevant. So I took on the task of removing all the old code that I could find. FoxReplace made the task easier but still took several hours to get it done. Doing any small change on the site with this many pages/categories/pages is always a chore. Hoping it doesn't hurt anything with SEO (would be nice if it helped). Just thought I'd share. Below is some of the random code that was leftover for all these years. `<!--mstheme--><span style="font-family: Arial;">` `<!--mstheme--><!--msthemelist-->` `<!--mstheme--></span><!--msthemelist-->`