Rust-built PSSA model outpaces transformer in speed and loss on WikiText-103 test
A developer built PSSA, a non-transformer language model coded from scratch in Rust without any ML framework, using a recurrent state-space layer, an episodic memory bank, and weights that update while the model runs. Tested against a matched-parameter standard transformer on identical data, PSSA reached a training loss of 3.98 versus the transformer's 4.43 over 12.7 million tokens, and generated text about twelve times faster on the same CPU. On a held-out 198,939-token slice neither model trained on, PSSA also scored lower loss throughout every checkpoint.
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The comparison suggests that for smaller-scale language modeling tasks, alternatives to the transformer architecture built around linear-cost recurrent state and explicit memory lookup could offer meaningful efficiency gains over the standard quadratic-cost attention approach. Because the tests were run at matched parameter counts and on a single corpus, it remains unclear whether these advantages would persist at the much larger scales and diverse datasets typical of production language models. The independent, framework-free implementation could also make the architecture easier to inspect and modify than mainstream deep learning stacks.
- PSSA is a recurrent, memory-augmented language model built from scratch in Rust with no ML framework dependencies.
- In matched-parameter tests on WikiText-103, PSSA achieved lower training and held-out loss than a standard transformer while running about 12x faster on CPU.
- The performance gap held consistently across every checkpoint on both training and unseen data, though results are so far limited to this specific small-scale comparison.
Source: github.com, 2026-09-30
Published there as: “PSSA: A non-transformer language model written from scratch in Rust”
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