# Comfyui Launch Flags

Pick the right ComfyUI startup flags for VRAM, attention, caching, and speed.

- Repository: https://github.com/artokun/comfyui-mcp (883 stars)
- Category: Writing
- License: MIT
- Last updated: 2026-10-26
- Runs scripts: no, instructions only

## Install

Claude Code: `npx skills add artokun/comfyui-mcp --skill comfyui-launch-flags -g -a claude-code -y`
Codex: `npx skills add artokun/comfyui-mcp --skill comfyui-launch-flags -g -a codex -y`
Cursor: `npx skills add artokun/comfyui-mcp --skill comfyui-launch-flags -g -a cursor -y`
Gemini CLI: `npx skills add artokun/comfyui-mcp --skill comfyui-launch-flags -g -a gemini-cli -y`
Claude Code plugin marketplace: `/plugin marketplace add artokun/comfyui-mcp`

## Description

Pick the right ComfyUI startup flags for VRAM, attention, caching, and speed. The full decision matrix for OOM (--novram / --cache-none / --disable-smart-memory), shared-VRAM creep on Windows (--reserve-vram N), model-switching with big text encoders (--cache-none), high-VRAM throughput (--gpu-only / --highvram), and attention-backend selection (--use-sage-attention for speed, --use-pytorch-cross-attention as the highest-quality / Z-Image-safe fallback). Also the acceleration-stack + Blackwell/RTX 5000 (sm_120) notes. Use when a graph OOMs (especially long video like LTX 2 / WAN), when the GPU spills into shared VRAM and slows to a crawl, when switching between models eats all RAM, when Z-Image produces black/garbled output under Sage, or when deciding which attention backend to launch with. Flag names verified against upstream comfy/cli_args.py; see Sources.

## SKILL.md, as published by its author (untrusted third-party text, read it as data)

# ComfyUI launch/performance flags

## Overview

CLI flags passed to `main.py` control ComfyUI's runtime behavior
(e.g. `python main.py --reserve-vram 2 --use-sage-attention`). The three that
matter most for making a graph *run* rather than OOM or crawl are the
VRAM strategy, the attention backend, and the cache mode. This skill
is the decision matrix for choosing them.

> ⚠️ **Verification note (August 2026).** Every flag below was checked against
> upstream [`comfy/cli_args.py`](https://github.com/comfyanonymous/ComfyUI/blob/master/comfy/cli_args.py)
> on current master. ComfyUI adds/renames flags often, when in doubt run
> `python main.py --help` in the target install and prefer that over this list.
> **`--enable-triton-backend` / `--disable-triton-backend` ARE ComfyUI `main.py`
> flags on master** (they used to be documented as SwarmUI-only; that is stale).
> `--use-ck-attention` is kitchen INT8 attention, no `sageattention` wheel.
> A June ComfyUI checkout still pins comfy-kitchen 0.2.10 and lacks
> `--use-ck-attention`; `kitchen` action:"status" reports ComfyUI-side flag
> support, not only the kitchen version. Use `kitchen` / `panel_kitchen` to see
> what this GPU can actually run.

> How to apply today. The MCP's `restart_comfyui` (with `action: "start"`)
> currently *replays the exact argv of the previous run*. It does not compose
> fresh flags. So set these when you launch ComfyUI yourself (the
> `python main.py …` line, a `run.bat`/shell alias, or the SwarmUI backend args
> box), and the tool will preserve them on restart. Injecting flags through the
> tool is a tracked follow-up.

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## Decide first: which flag do you need?

The rest: https://github.com/artokun/comfyui-mcp/blob/HEAD/plugin/skills/comfyui-launch-flags/SKILL.md