Low Interpolation Delay vs. High Snapshot Buffer for Jitter Tolerance

Networking Trade-offs in Source Engine

In the original Source Engine networking model, clients render remote entities in the past to ensure smooth movement via interpolation. This process relies on the cl_interp and cl_interp_ratio variables to determine how many snapshots are buffered before rendering.

A primary design conflict arises when balancing the perceived responsiveness of hit registration against the stability of entity movement under suboptimal network conditions. Minimizing the interpolation buffer reduces the time difference between the client's view and the server's current state, which mitigates the "shot behind cover" effect for victims. However, this leaves the client with a smaller safety margin to handle packet jitter or loss.

Conversely, increasing the interpolation ratio provides a smoother experience for players with unstable connections but increases the effective latency that the server's lag compensation system must rewind during hitscan calculations.

• Low Interpolation: Prioritizes temporal accuracy and reduces rewind distance, but risks entity stuttering during packet arrival variance.
• High Interpolation: Prioritizes visual fluidity and jitter tolerance, but increases the discrepancy between client view and server state.

Given these constraints, what is the optimal balance for sv_client_min_interp_ratio on a high-tickrate server to prevent stuttering without introducing excessive lag compensation windows? Under what specific network jitter thresholds does the benefit of a higher interpolation buffer outweigh the cost of increased effective latency?