gzip wont be worth the time, the more and more links and images that get added to each main index page just adds to the problem. So the best solution is for each game to have their own individual page, so the URL's will be something like:
vgmaps.com/nes/batman
vgmaps.com/nes/batmanreturns
vgmaps.com/snes/smb
vgmaps.com/snes/smb2
etc, etc.
That way the NES, SNES, etc Map index pages can just be links to those pages, so it wont need the game logos on the Atlas index pages, nor would it have links to the thousands of maps for every single game all on one page. The logos and individual map links would be on the individual pages (vgmaps.com/snes/smb would display the game logo, and all links to maps of that game)
A few other things:
1. You should use all lowercase letters on URL's, not like this: (Atlas/SuperNES) and (NewsArchives/MapsOfTheMonth)
2. The URL's of the pages are too long (vgmaps.com/Atlas/SuperNES/index.htm) should be changed to (vgmaps.com/snes)
(vgmaps.com/NewsArchives/MapsOfTheMonth-2015.htm) to (vgmaps.com/motm/2015)
(vgmaps.com/Atlas/index.htm) to (vgmaps.com/atlas) etc, etc
A simple code can be used to automatically forward (Atlas/SuperNES/index.htm) to (snes), so anyone who has that bookmarked will automatically be sent to the correct page, and they get sent immediately without even noticing that the page was forwarded.
3. You should also stop using .htm extensions completely
4. Some of the fonts on the home page are way too small, the fonts on the left Atlas Menu's, and the fonts for the site updates.
5. New tables need to be created for the map links, new modern tables styled with CSS, different than the ones the site currently has.
6. The website needs a new logo, maybe that same font can be used, but the current logo reminds me of web sites created back in the 1990's.
7. Those Casino ads on the main home page should probably go, any sites that display ads like that usually get a bad reputation, also people tend to think those ads lead to virus or spam sites.
8. Project Wonderful should probably go as well, there are much better ad networks out there, I can recommend some.
For me, setting up the new layout and how the links will be displayed on the main Atlas pages, changing/forwarded the longer .htm URL's, and creating the codes best suited for the CSS tables for the map links is all very easy. I already have the entire layout in my head without even having to write anything down to remember. It will be an easy to use layout.
But the long, hard part will be adding the thousands of maps to the new layout. But in the end it will be all worth it, with the new layout you can easily add thousands and thousands of maps without hurting load time for users.