
ZO-Act: Efficient Zeroth-Order Fine-Tuning via One-Shot Activation-Informed Low-Rank Subspaces
ZO-Act addresses a critical bottleneck in LLM adaptation: fine-tuning without backpropagation access or sufficient memory. By anchoring perturbations to activation-derived low-rank subspaces rather than random projections, the method cuts variance and computational overhead while enabling standard optimizers like Adam. This matters for practitioners deploying models on edge hardware, in restricted API environments, or under extreme memory constraints. The technique signals growing sophistication in zeroth-order methods, a category increasingly relevant as model sizes outpace available GPU memory and closed-model APIs limit gradient access.62























