Continued pretraining vs RAG on Qwen 3.5 4B: a hands-on accuracy and performance comparison

funJS · reddit · 2026-09-12

The author ran a controlled experiment comparing a Qwen 3.5 4B model fine-tuned with continued pretraining via Unsloth against a RAG setup on the base model, measuring accuracy and inference performance to quantify the benefit of internalizing knowledge versus on-the-fly retrieval. Full write-up linked in the post.

Related event: CPT vs RAG: Testing Knowledge Internalization on Qwen 3.5 4B(3 posts)→

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