Is Qwen3.5-4B-heretic or LFM2.5-VL-1.6B smaller?

LFM2.5-VL-1.6B is smaller at Q4_K_M: 0.68 GiB against 2.52 GiB.

Which uses less memory at long context?

LFM2.5-VL-1.6B — its KV cache at 32K context is 2.7x smaller, because of how its attention layers cache.

Model comparison

Qwen3.5-4B-heretic vs LFM2.5-VL-1.6B

At Q4_K_M, LFM2.5-VL-1.6B is the smaller download — 730,895,968 bytes against 2,708,804,384. At long context the gap widens: LFM2.5-VL-1.6B's KV cache at 32K is 2.7× smaller, which usually matters more than the difference in weights.

From the file· summed bytes, KV per layer

Side by side

	Qwen3.5-4B-heretic	LFM2.5-VL-1.6B
Parameters	4.5B	1.6B
Architecture	qwen35	lfm2
Layers	32	16
Native context	262,144	128,000
Mixture of experts	no	no
Quantizations published	6	23
Smallest quantization	0.64 GiB	0.45 GiB
Q4_K_M	2.52 GiB	0.68 GiB
Licence	apache-2.0	other

KV cache by context

the term that decides long-context viability

Context	Qwen3.5-4B-heretic	LFM2.5-VL-1.6B	Ratio
4,096	0.13 GiB	0.05 GiB	2.67×
8,192	0.25 GiB	0.09 GiB	2.67×
16,384	0.50 GiB	0.19 GiB	2.67×
32,768	1.00 GiB	0.38 GiB	2.67×
65,536	2.00 GiB	0.75 GiB	2.67×
131,072	4.00 GiB	1.50 GiB	2.67×