ComfyUI-GraphConstantFolder

ComfyUI-GraphConstantFolder

A server-side ComfyUI extension that rewrites the submitted prompt graph before validation to constant-fold switch/selector nodes and optionally prune now-unreachable branches.

This targets the common performance bottleneck in large workflows where ComfyUI’s prompt validation recursively traverses linked upstream nodes even when a conditional branch will not execute.

[!NOTE] In some workflows this can also act as a practical workaround for ComfyUI validation failures involving nested subgraphs and lazy switch nodes, especially with comfyui-execution-inversion. By folding prompt-time-constant branches before validation, it can avoid backend recursion through inactive paths. This is a workflow-dependent workaround, not a guaranteed fix for all subgraph issues.

Works best with

This extension is designed to be used in tandem with node packs that provide conditional routing:

• comfyui-execution-inversion — provides LazySwitch, LazyIndexSwitch, LazyConditional
  • https://github.com/BadCafeCode/comfyui-execution-inversion
• ComfyUI-KJNodes — provides LazySwitchKJ
  • https://github.com/kijai/ComfyUI-KJNodes
• akatz-loop-nodes — provides LazySwitch | akatz-loops, LazyIndexSwitch | akatz-loops, LazyConditional | akatz-loops
• ComfyUI-Lazy-Fallback-Switch — provides fixed and Autogrow fallback switches

It can also fold non-lazy switch-like nodes when their decision input resolves to a prompt-time constant.

What it does

1. Constant-folding: if a switch decision is constant at prompt submission time, it rewires downstream links so consumers connect directly to the selected branch.
2. Pruning (optional): if PRUNE=1, it removes nodes that become unreachable upstream of the execution targets (output nodes or partial-execution targets).

Folding targets

Lazy switches

• LazySwitch / LazySwitchKJ (boolean switch, on_true, on_false)
• LazyIndexSwitch (integer index, value0..valueN)
• SparknightLazyFallbackSwitchStatic (integer index, value0..value9, default)
• SparknightLazyFallbackSwitch (integer index, Autogrow values.valueN, default)
• LazyConditional (conditionN, valueN, else)

Display-name suffixes such as | akatz-loops are normalized before matching.

Switch-like nodes (non-lazy)

If a node exposes one of these exact input signatures, it is treated as a switch and can be folded when the decision is constant:

• switch, on_true, on_false
• condition, if_true, if_false
• index with value0, value1, ...

Install

Copy this folder to:

ComfyUI/custom_nodes/ComfyUI-GraphConstantFolder

Restart ComfyUI. You should see:

[GraphConstantFolder] installed on_prompt handler (constant-fold: lazy switches + switch-like nodes)

Configure

You can use either environment variables or the local config file.

Environment variables

• GRAPH_CONSTANT_FOLDER_ENABLED=1 (or GCF_ENABLED=1)
• GRAPH_CONSTANT_FOLDER_PRUNE=1 (or GCF_PRUNE=1)
• GRAPH_CONSTANT_FOLDER_DEBUG=1 (or GCF_DEBUG=1)
• GRAPH_CONSTANT_FOLDER_VERBOSE=1 (or GCF_VERBOSE=1)

Config file

Edit graph_constant_folder_config.json next to graph_constant_folder.py:

{
	"ENABLED": 1,
	"DEBUG": 0,
	"VERBOSE": 1,
	"PRUNE": 1
}

Environment variables override the config.

Extending constant resolution (safe)

By default, the extension resolves prompt-time constants through:

• literal values in the prompt JSON
• Reroute-like pass-through nodes
• constant/primitive/literal nodes (by class name match) only when they have no linked inputs
• EnumCombo / EnumComboAdvanced integer outputs when the enum definition and selected choice are prompt-time constants
• CM_IntBinaryCondition boolean outputs when both integer inputs and the comparison op are prompt-time constants

To extend the constant-source class matcher, set:

• GRAPH_CONSTANT_FOLDER_CONST_CLASS_TYPES="(?i)(primitive|constant|literal|impact.*primitive|rgthree.*primitive)"

This does not evaluate boolean logic (AND/OR/compare), so it remains conservative.

Example output

[GraphConstantFolder] on_prompt: nodes=203, switch_candidates=23, foldable=11, prune=1, verbose=1
[GraphConstantFolder] rewrote nodes=20, pruned=105, dt_ms=4.36
Prompt executed in 0.08 seconds

Without the extension, the same ~200 node workflow incurs a "get prompt" delay of about 0.5 seconds.