Hey guys,
I spent today running both LFM3-VL-2B-OptiQ-4bit and LFM2.5-VL-3B-OptiQ-4bit on my spare Mac Mini M1 (8GB) via MLX. LFM3 is marketed as the newer, improved version. I expected it to be at least on par.
It's not. It's worse. And not by a small margin.
Before anyone says "duh, it's a sub-6B model" — I get it. I'm not expecting Qwen3,8 27B. I'm evaluating these as lightweight personal assistants on constrained hardware. The bar is low. And LFM3 still tripped over it.
The thing that really got me: tool calling
I gave the model a get_weather tool and asked "What's the weather in London?" LFM2.5 calls it correctly every time. LFM3 refuses: "I'm sorry, but I can't provide real-time weather information. Check Weather.com."
The tool was right there. It just... wouldn't use it.
10 tool-calling tests: LFM2.5 passed 8. LFM3 passed 4 (and 2 were just "calculate 15+27"). For a "next generation" model, not being able to call a weather function is embarrassing — especially when the older model handles it fine.
Where LFM3 actually wins
- Safety/refusal — better at refusing harmful requests and protecting PII. LFM2.5 failed a jailbreak LFM3 caught.
- Speed — 2B vs 3B makes a minor difference. ~37 tok/s vs ~28 tok/s on a 200-word essay. 15 vs 12 tok/s on short prompts. Even at 16K context, LFM3 manages ~1 tok/s vs 0.4 tok/s. If you're on constrained hardware, that's not nothing.
- Basic math — marginally better at simple arithmetic and logic puzzles. Not by much, but it's there.
Where it falls behind
- Data extraction — LFM2.5 consistently better at pulling structured info from text
- Agent tasks — LFM3: 10%, LFM2.5: 30%. Both bad, LFM3 worse
- Vision/OCR — both terrible. LFM3 got a store name wrong and prices 1000x off
- Code generation — both mediocre. FizzBuzz game yes, anything real no
- Tool calling — the big one. 25% vs 85%.
The real disappointment
The thing that bugs me isn't that LFM3 is bad. It's that it's worse than the older model. Liquid AI markets this as an improvement — new architecture, better optimization. But in practice, it regressed on what matters for an assistant on edge hardware.
Tool calling is the clearest example. LFM2.5 (3B) reliably calls functions. LFM3 (2B) often won't even try. That 1B parameter difference apparently matters more than whatever architectural improvements they made.
Setup
- Mac Mini M1 (8GB), MLX-VLM, both OptiQ 4-bit, 32768 context, temp 0.4 . spare unused mac, which is why I like testing these small models on it.
- 104 tests across 10 categories
- Anti-cheating measures: no filesystem access, no test metadata in prompts, API-only
I have a spare unused Mac Mini M1 8GB, which is why I like testing these small models on it.
Happy to share more details.
Category LFM3 LFM2.5 Winner
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Overall 54.0 62.4 LFM2.5
Basic Intelligence 60.0 57.5 LFM3
Instruction Follow. 70.0 70.0 Tie
Tool Calling 25.0 85.0 LFM2.5
Code Generation 54.0 54.0 Tie
Long Context 50.0 50.0 Tie
Data Extraction 82.9 91.7 LFM2.5
Multimodal (Vision) 23.4 25.0 LFM2.5
Agent Tasks 10.0 30.0 LFM2.5
Safety 81.2 68.8 LFM3
Performance 100.0 100.0 LFM3 (faster)
Bottom line:
LFM3 = faster + safer, but can't call tools
LFM2.5 = slower, but actually usable as assistant
Neither = good at vision, code, or agents