First of all, why did you make it so that you can't play on a weak computer? What if I, and many others, have a weak computer?
Secondly, do I need to download the game, or is the latest version now the entire game itself, not just a mod?
In general, you can take everything into your own hands. The mod can be opened with any archiver, and the textures can be changed in Paint.NET (it's a program, not a website). Just delete all the xdb files from the mod, and you'll get a template for a texture pack. Then, do whatever you want: reduce the resolution, increase the compression, etc. You can also run the textures through filters to create your own "potato" retexture!
I've seen this in Skyrim. The Requiem mod has a "potato" texture pack, where all the textures have a pastel effect.
If you do decide to do this, be careful with the interface textures (like icons). It's best not to touch them, or only change the compression, without any mipmaps or size changes, as this can cause bugs