QUIC is not Quick Enough over Fast Internet

TL;DR

This paper systematically examines QUIC's performance over high-speed networks, revealing significant data rate reductions and identifying high receiver-side processing overhead as the main cause, with recommendations for mitigation.

Contribution

It provides a detailed analysis of QUIC's performance issues over fast Internet and offers concrete mitigation strategies, which is a novel contribution.

Findings

QUIC suffers up to 45.2% data rate reduction on fast networks.

Performance gap between QUIC and HTTP/2 increases with bandwidth.

High receiver-side processing overhead causes performance issues.

Abstract

QUIC is expected to be a game-changer in improving web application performance. In this paper, we conduct a systematic examination of QUIC's performance over high-speed networks. We find that over fast Internet, the UDP+QUIC+HTTP/3 stack suffers a data rate reduction of up to 45.2% compared to the TCP+TLS+HTTP/2 counterpart. Moreover, the performance gap between QUIC and HTTP/2 grows as the underlying bandwidth increases. We observe this issue on lightweight data transfer clients and major web browsers (Chrome, Edge, Firefox, Opera), on different hosts (desktop, mobile), and over diverse networks (wired broadband, cellular). It affects not only file transfers, but also various applications such as video streaming (up to 9.8% video bitrate reduction) and web browsing. Through rigorous packet trace analysis and kernel- and user-space profiling, we identify the root cause to be high receiver-side processing overhead, in particular, excessive data packets and QUIC's user-space ACKs. We make concrete recommendations for mitigating the observed performance issues.