Amortized Latent Steering: Low-Cost Alternative to Test-Time Optimization
Test-time optimization (TTO) incurs prohibitively high inference overhead—10–100× that of standard decoding—due to iterative optimization and multi-step backpropagation, hindering practical deployment. To address this, we propose **Amortized Latent Steering (ALS)**, a gradient-free, constant-overhead alternative that eliminates online optimization. ALS precomputes, offline, the mean difference vector between latent states of successful and failed examples, enabling efficient, zero-gradient latent-space calibration at inference time. By integrating directional latent-space steering with a mean-field approximation, ALS achieves 2–5× speedup over iterative TTO on GSM8K and MATH-500 while improving the efficiency–accuracy trade-off by 101%. It matches or surpasses greedy chain-of-thought and Self-Consistency baselines in accuracy, marking the first practical, low-latency, high-accuracy deployment of TTO without backpropagation.