This is an interesting request. Not a bad request, but interesting.
If what you need is better framerate and smoother play, then there are a number of things you can do with what exists right now. First and most importantly, you need to check the Tweak Guide for Fallout: New Vegas. The reason you start there is that the guide covers in-game controls and .ini settings, all without using mods at all. Each variable is explained in detail, to let you know what it does and how much impact it has on framerate and CPU usage. It's a long read, but if you're serious about this, you will probably enjoy learning these "behind the curtain" settings.
I know you don't want to have to use "those mods that glitch out the game [performance mods]," but the fact is those are the second place to go. I have used these myself, on multiple computers of different architecture and power, and I have never had an issue with any of them. I also made damned sure I followed the instructions carefully, and when I could, I found tutorials (usually by Gopher) to make sure I understood what I was doing.
The most important is 4GB Fallout: New Vegas Updated. This allows the game to recognize that you have more than 2GB of memory (if indeed you do...if you run Windows XP or newer, you probably do). Most of the time, when you have lag or stutter, it's because your computer is running out of memory to juggle everything happening in the game all at once. This alone will probably make the single greatest difference for your game.
Next, New Vegas Stutter Remover. I automatically install this alongside of 4GB. Does what it says on the box, by (if I understand/remember correctly) flushing memory every so often so there is always plenty of elbow room for more data.
There are other suggestions. Use Mod Organizer rather than NMM, because it doesn't hose up your Data folder. Set graphic settings in-game to Small texture sizes. Make sure you check and know (and adjust, where needed) the settings for your graphics card. If you really want what you say you want, you won't choke on the thought of doing these simple things, and being mindful about it will be well worth it.
Then again, if all you want is cel-shading or cartoony graphics...well, that's a horse of a different color.