Recently I tried Fooocus by Lyumin Zhang (Illyasviel) which fulfills its promise to allow one to “Focus on prompting and generating” - it is certainly easy to use! But shortly after its release, someone has “ported” the code to ComfyUI as a Custom Node! So of course it’s time to test it out...

About Fooocus

Among the many enhancements, Fooocus implements a “native refiner swap inside one single k-sampler... Fooocus uses its own advanced k-diffusion sampling that ensures seamless, native, and continuous swap in a refiner setup.” Compare this to using two sampler nodes in ComfyUI.

Install ComfyUI_Fooocus_KSampler

I noticed a post by GerardP19 on Reddit, entitled “My new workflow utilizing the Foocus sampler in Comfy, with the styler and nested nodes. ” but he did not provide a link to his GitHub repo, instead requiring ComfyUI-Manager to install.


  • Download ComfyUI_Fooocus_KSampler.
  • Unzip and place the folder in ComfyUI\custom_nodes.
  • Start (or re-start) ComfyUI.
  • Create a workflow to test...

At time of writing, there is bug with the Fooocus KSampler extension which may be fixed by the time you read this! If so, ignore the following:

Error! Cannot import ...\ComfyUI\custom_nodes\ComfyUI_Fooocus_KSampler-main module for custom nodes: cannot import name 'load_additional_models' from 'comfy.sample'

  • Edit the file ComfyUI_Fooocus_KSampler-main\sampler\Fooocus\
  • Search for load_additional_models.
  • Compare with similar function in ComfyUI get_additional_models .
  • Search for all instances of load_additional_models to replace with get_additional_models:
    • replace in from comfy.sample import prepare_mask, broadcast_cond, load_additional_models, cleanup_additional_models
    • replace two instances of models = load_additional_models(positive, negative, model.model_dtype()) with models = get_additional_models(positive, negative)
  • Re-start ComfyUI and re-test.

I encountered this error with my specific computer setup, but you may not!

Error! RuntimeError: [enforce fail at ..\c10\core\impl\alloc_cpu.cpp:72] data. DefaultCPUAllocator: not enough memory: you tried to allocate ###### bytes.

I encountered this previously, but I just worked around it by splitting my workflow into two discrete steps (Base and Refiner), though sometimes re-running the workflow managed to squeeze everything in memory since the nodes cache outputs. Just wrongly assumed I did not have enough VRAM and mentioned this in a previous post, but that’s not the root cause!

I now realize it’s because I have too little system RAM, only 16GB! One solution is to buy more... but for now, increasing the Windows virtual memory paging file size allows me to continue:

  • From the Start Menu, type View advanced system settings.
  • In the System Properties panel, navigate to the Advanced tab > Performance Settings...
  • In the Performance Options panel, again navigate to the Advanced tab
  • Under Virtual Memory, click Change...
  • Disable Automatically manage paging file size for all drive and manually specify a Custom size: I set a range from 18000 MB to 30000 GB
  • Click Set to save, then back out of the panels by clicking the OK buttons.

No-Code Workflow

At minimum:

  • A CheckpointLoaderSimple node to load SDXL Base.
  • A CLIPTextEncodeSDXL and a CLIPTextEncode node for the positive and negative prompts.
  • A CheckpointLoaderSimple node to load SDXL Refiner.
  • A CLIPTextEncodeSDXLRefiner and a CLIPTextEncode for the refiner_positive and refiner_negative prompts respectively.
  • A EmptyLatentImage specifying the image size consistent with the previous CLIP nodes.
  • Wire up everything required to a single KSampler With Refiner (Fooocus) node - this is so much neater!
  • And finally, wire up the latent output to a VAEDecode node followed by a SameImage node, as usual.

ComfyUI workflow with Fooocus KSampler Custom Node

For the curious, prompt credit goes to masslevel who shared “Some of my SDXL experiments with prompts” on Reddit. And as a teaser... coming up, SDXL ControlNet for OpenPose (v2) !