Greetings!

Well, after reaching 100hrs of gameplay I'm finally at the point where the game gets unplayable due to constant crashing.

Basically what happens is that I load my file and after literally a minute it crashes no matter what I do.

I last saved in the Rivet City marketplace because I was in a expedition to sell some gear. I prefer walking while exploring but when I do the whole selling stuff, that's when I abuse the fast traveling option.

I play GOG's version of FO3 GOTY on Windows 10. No extra stuff added like mods or texture packs, tho I've used console commands a couple of times to get things that glitched through walls or a last minute ingredient to craft something. Or just to check unobtainable items.

I have the auto-save while fast travel and save while entering a new building option disable, I only kept the saving while sleeping enable.

Yes, I'm aware that there are mods and unofficial patches and whatnot, but I've been trying to get the full Fallout 3 Vanilla experience to see if the games holds on it's own, that's why I haven't installed anything yet. If I end up having no choice but install a third-party solution I'll do it, but I wanted to see if there's a simple solution withing reach. I dunno, maybe modifying a .txt or a .ini file?

I'd like to apologize if I made this post longer than it should've been but I wanted to share what I've done just in case it has some kind of relevance to the cause of this issue. I dunno man, it's a freaking Bethesda game, it's a miracle they don't make your PC explode.

As a matter of fact you could try editing an ini file.
Open "%USERPROFILE%\Documents\My Games\Fallout3\FALLOUT.ini" using a text editor. Locate the line "iNumHWThreads=2" and edit it to "iNumHWThreads=1" (you can also experiment with other values such as 4: this value indicates how many CPU threads the game will use). Now save the file and run the game.

Consider that I suspect you are experiencing random crashes due to multi-core CPU but I'm not sure at all: if the game used to work correctly in the past, these crashes could be simply due to a corrupted savegame. Please, try different savegames and see if the game crashes randomly before tweaking ini file.

You can also read this guide for further help.

This is hard to believe, however I'm not familiar with console commands and their consequences on stability.
Load one of your savegames, then open the console and issue the following command: pcb (Purge Cell Buffer). Now play the game and see if it is more stable. Honestly I'm not sure if this would help at all, but I was thinking that purging the game cache could influence its stability.