If you’ve ever experimented with AI image generation in Fooocus, you’ve probably noticed several options like Quality, Speed, Extreme Speed, Lightning, and Hyper-SD.
At first glance, they may seem like simple “fast or slow” choices, but there’s more going on behind the scenes. Each mode changes how the model processes your prompt, how much GPU power it uses, and how the final image turns out.
Let’s break down exactly what these modes mean — and one crucial detail many users don’t realize about Extreme Speed, Lightning, and Hyper-SD modes.
Quality: Maximum Detail, Minimum Rush
The Quality mode is the best choice for artists who want perfection.
It uses more diffusion steps, stronger refinement passes, and considers all your prompt settings — including negative prompts, guidance scale, and image sharpness.
It results to Images with deeper contrast, realistic lighting, and more accurate details.
- Speed: Slowest
- GPU Usage: High
- Best for: Portraits, product renders, and final images you plan to publish.
If you need realism or cinematic composition, this is where Fooocus truly shines.
Speed: Balanced and Efficient
The Speed mode offers the perfect middle ground. It keeps much of the visual quality of “Quality Mode” but processes faster by cutting a few refinement layers.
It still uses negative prompts, guidance scale, and sharpness settings, which means you can fine-tune the output precisely.
- Speed: Faster than Quality
- GPU Usage: Moderate
- Best for: Drafts, social media graphics, and everyday AI generation.
Speed mode is ideal when you want consistent quality without waiting too long.
Extreme Speed: For Instant Results
Extreme Speed does what its name promises — generates images in seconds.
However, this mode completely ignores negative prompts, guidance scale, and image sharpness.
That means you can’t refine the model’s behavior as much. The AI skips several steps to achieve speed, giving you images that might look less refined or slightly random.
- Speed: Very fast
- GPU Usage: Low
- Ignored Settings: Negative prompt, guidance scale, image sharpness
- Best for: Rough concepts or testing ideas quickly.
Extreme Speed is fantastic when you want to “see something now,” not when you need perfect results.
Lightning Mode: Real-Time Generation
Lightning Mode is built for speed enthusiasts and live experimentation.
It uses the Lightning SD model, designed for real-time or near-instant image generation with as few as 1–4 sampling steps.
But like Extreme Speed, Lightning Mode ignores negative prompts, guidance scale, and sharpness.
You can’t control how soft or hard the model interprets your prompt — it just delivers the fastest possible output.
- Speed: Extremely fast
- GPU Usage: Very low
- Ignored Settings: Negative prompt, guidance scale, image sharpness
- Best for: Interactive sessions, idea testing, and quick visual previews.
If you’re tweaking prompts rapidly and just want a visual direction, Lightning Mode is unbeatable.
Hyper-SD Mode: Fast and Surprisingly Sharp
The newest generation of speed presets is Hyper-SD — an optimized checkpoint or LoRA designed for ultra-fast diffusion while keeping better clarity than Lightning.
Unlike Quality or Speed mode, Hyper-SD also does not use negative prompts, guidance scale, or image sharpness.
Instead, it relies on internal hyper-optimized weights that simulate balanced diffusion in only a few steps.
- Speed: Lightning-fast
- GPU Usage: Medium to low
- Ignored Settings: Negative prompt, guidance scale, image sharpness
- Best for: Speedy, clear results with minimal tweaking.
If you want images fast and still fairly clean, Hyper-SD gives you the best of both worlds.
Quick Comparison
| Mode | Quality | Speed | GPU Load | Negative Prompts / Guidance | Best For |
|---|---|---|---|---|---|
| Quality | Slow | High | Yes | Final renders, realism | |
| Speed | Medium | Medium | Yes | Fast-quality balance | |
| Extreme Speed | Fast | Low | No | Rough previews | |
| Lightning | Extremely Fast | Very Low | No | Instant generation | |
| Hyper-SD | Extremely Fast | Very Low | No | Clean + fast results |
Final Thoughts
Fooocus gives you the freedom to choose between speed and precision.
If you’re building your final images — use Quality or Speed mode.
But if you’re brainstorming or testing many prompts quickly, Extreme Speed, Lightning, and Hyper-SD can save you massive time.
Just remember that the extremely fast modes don’t honor negative prompts, guidance scale, or sharpness adjustments, so your control is limited. The key is to use fast modes for exploration, then switch back to Quality or Speed when you’re ready for your masterpiece.
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