I would guess it's one of three things:
- You are using Windows instead of Linux for ROCm (I don't know how much this affects performance, as I am only on Linux)
- You are generating the batch all at the same time, instead of just doing multiple generations. This can lead to out-of-memory issues, as it is a larger image being generated.
- You are not fully using the GPU. Does task manager say 100% utilization?
The usefulness of ComfyUI is not just making one simple image. It is the ability to completely customize how that image is created.
For example, I have a workflow that generates a half-resolution preview image, then upscales the latent and puts it through two more sampling nodes. All three of the nodes have a different prompt input, with the focus slowly shifting to style instead of content.
I have also created a custom upscaling workflow, where the image is upscaled with normal upscaling, then re-encoded and put through just a few sampling steps, the re-encoded with a tiled VAE decoder (to save my VRAM). It creates much better results (more detail and control) than a direct ERSGAN upscale, and can even be put through ERSGAN afterward to get a super large image.