Title: Curvature-Aware Residual Prediction for Stable and Faithful Diffusion Transformer Acceleration Under Large Sampling Intervals
Primary area: generative models
Keywords: Generative Models

Abstract: Diffusion Transformers have achieved remarkable performance in generative tasks, yet their large model size and multi-step sampling requirement lead to prohibitively expensive inference. Conventional caching methods reuse features across timesteps to reduce computation, but introduce approximation errors that accumulate during denoising—a problem exacerbated under large sampling intervals where significant feature variations amplify errors. Recent prediction-based approaches (e.g., TaylorSeers) improve efficiency but remain limited by sensitivity to feature variations across distant timesteps and the inherent truncation errors of Taylor expansions.
To address these issues, we propose a novel **C**urvature-**A**ware **R**esidual **P**rediction (CARP) framework, which shifts the prediction target from raw features to residual updates within Diffusion Transformer blocks.  We observe that residuals exhibit more stable and predictable dynamics over time compared to raw features, making them better suited for extrapolation. Our approach employs a rational function-based predictor, whose theoretical superiority over polynomial approximations is rigorously established: the numerator performs linear extrapolation using adjacent features, while the denominator incorporates discrete curvature to adaptively modulate the strength and behavior of the prediction. This design effectively captures the alternation between gradual refinements and abrupt transitions in diffusion denoising trajectories. Additionally, we introduce a curvature-guided gating mechanism that regulates the use of predicted values, enhancing robustness under large sampling steps. Extensive experiments on FLUX, DiT-XL/2, and Wan2.1 demonstrate our method's effectiveness. For instance, at 20 denoising steps, we achieve up to 2.88× speedup on FLUX, 1.46× on DiT-XL/2, and 1.72× on Wan2.1, while maintaining high quality across FID, CLIP, Aesthetic, and VBench metrics, significantly outperforming existing feature caching methods. In user studies on FLUX, CARP receives nearly 25\% more preference than the second-best method. These results underscore the advantages of residual-targeted prediction combined with a rational function-based extrapolator for efficient, training-free acceleration of diffusion models.