CacheBrowser achieves significantly lower download latency than Tor when fetching CDN-hosted content from China, because content is retrieved directly from CDN edge servers without traversing third-party proxies. Fetching from non-default alternative CDN edge servers increases latency relative to the CDN-mapped optimum, but the overhead is not prohibitive for real-world browsing; geographically proximate alternative servers minimize the penalty.
From 2015-holowczak-cachebrowser — CacheBrowser: Bypassing Chinese Censorship without Proxies Using Cached Content
· §5.3
· 2015
· Computer and Communications Security
Implications
Publisher-centric circumvention via CDN bypasses proxy relay overhead and outperforms Tor on latency for CDN-hosted content; tool designers should evaluate CDN-bypass as a complement or replacement for proxy transports on popular blocked sites.
Tools should maintain region-annotated CDN edge-server databases and prefer geographically proximate servers, as proximity to the censored user is the dominant factor in keeping latency overhead acceptable when bypassing the CDN mapping system.