ApplyFirstBlockCachePatch

This is the plain version of ApplyFirstBlockCachePatchAdvanced: same First Block Cache trick, one less knob. It runs the transformer's first double block as a cheap probe, compares its output to the previous step's, and when they're close enough it skips the rest of the double blocks and the single blocks, reusing the last fully-computed result. For Flux at 20+ steps that's a lot of skipped work, and it's why this node family gets you roughly 1.8x on Flux without retraining anything.

The Advanced sibling adds start_at/end_at so you can confine caching to the middle of the denoising schedule. This one caches the whole run, which is simpler to reason about - you just trade one dial.

The one dial

• residual_diff_threshold - how similar a step must look before it's skipped. Higher = more skipping = faster and fuzzier. Author's reference values: Flux 0.12 ≈ 1.8x, HunYuanVideo 0.1 ≈ 1.6x, LTXVideo 0.05 ≈ 1.2x, MochiVideo 0.03 ≈ 1.5x, WanVideo 0.05 ≈ 1.5x. 0 turns it off completely, which also makes the node a harmless pass-through.

model in, model out. That's the whole interface - this is a "set it and forget it" node once you've found your threshold.

Wiring and install

It only does anything when a *ForwardOverrider is in the same model path (DitForwardOverrider auto-detects Flux versus video, FluxForwardOverrider and VideoForwardOverrider are the scoped versions). Chain: loader → cache patch → overrider → guider/KSampler.

Part of ComfyUI_Patches_ll:

cd ComfyUI/custom_nodes
git clone https://github.com/lldacing/ComfyUI_Patches_ll.git
# restart ComfyUI

ComfyUI Manager will find it as ComfyUI_Patches_ll. Needs ComfyUI ≥ 0.3.17; no model downloads, no heavy dependencies.

Gotchas

• MochiVideo is the pack's known weak spot - the README says accelerated output quality is poor and can fail, so skip it there.
• No speedup, no error. Missing overrider means the hooks never fire. That's the silent failure to check first.
• Smearing when pushed too far. If the image starts losing structure, back the threshold down.

If you think you might want caching only during the middle 20–80% of sampling (which is the classic safe window, and where aggressive Flux settings live), grab the Advanced version instead. Otherwise this one dial is all there is, and that's a feature.