Renderers decompress the textures.
Real-time 3d engines either use decompressed textures or gpu compression(DXTn), so it doesn't matter what kind of format you pass to them.>>522520
raw is terrible for real-time, a single 4096x4096 pixels texture is 4096*4096*32=536870912bits or 64MBs, 40 of those is more than the majority of modern gpus for gaming or for rendering for that matter can handle. And that's not considering the pixel fillrate limits. Another problem is that multiple gpus, while they can render faster, cannot share the memory, so even if you have 10 titans you're limited to the memory of 1.
Btw, if anyone is interested why that is, it's basically cause you have to load the whole scene even for 1x1 tile in order to have properly calculated color.>>522526
It's most likely due to the faster disk loading times, but I'm not sure. It doesn't really matter what kind of lossless format you use for rendering or real-time rendering for that matter(although it's better to use DXTn for real-time).