Razer chroma and rtx 4090

Can you confirm something for me? Is the efficiency loss of a 4090 inside of an eGPU mostly loss in bandwidth, since Thunderbolt 3/4 only goes up to 40Gbps which is much narrower than PCIE 4.0 x16? Does this mean that in workloads like Blender rendering or machine learning, where there is not a lot of data transfer going on, there would be no performance loss? If all I cared about was rendering performance, not gaming, would putting a 4090 in an eGPU still give me performance loss of 30%? I think in a Blender render, the whole project can fit in VRAM with GPU rendering, and since rendering each frame takes so long, the speed of transferring the rendered frame back from GPU VRAM to disk wouldn't matter so much since it will take another minute for the next frame to be rendered anyways. And even the slowest transfer rate on Thunderbolt probably wouldn't take more than 10 seconds to transfer a 5MB image from GPU to disk. I'm not 100% sure though.