Textures: A8R8G8B8 vs. DXT5 in-game performance (1 reply)

Hi all,
Does anyone know what sort of effect, if any, using A8R8G8B8 have on the running of the game, compared to DXT5?
When viewed in Slimtex, A8R8G8B8 is a much nicer looking result than a DXT5 image of higher resolution, but at the cost of a much larger size on-disk: A 2048x A8R8G8B8 .tex (from a 4096x TGA; Full Transparency) is about the same size on disk as a 4096x DXT5 .tex (with Full Transparency).
I assume that this outcome - better quality with larger file size - is simply the result of there being much less compression, and so I'd think that, if there was a performance gain to be had, it would be when the texture is loaded into memory by the game.
But this gain would only happen if the game uncompressed the textures before loading them into memory I think?

I can't think of how using A8R8G8B8 would negatively affect performance compared to DXT5, unless there wasn't enough memory to hold the textures.
If somebody (with a better idea than I of what they're talking about) has any idea, I'd love to hear it.