Illegal content on social media poses significant societal harm and necessitates timely removal. However, the impact of the speed of content removal on prevalence, reach, and exposure to illegal content remains underexplored. This study examines the relationship with a systematic audit of takedown delays using data from the EU Digital Services Act Transparency Database, covering five major platforms over a one-year period. We find substantial variation in takedown delay, with some content remaining online for weeks or even months. To evaluate how these delays affect the prevalence and reach of illegal content and exposure to it, we develop an agent-based model and calibrate it to empirical data. We simulate illegal content diffusion, revealing that rapid takedown (within hours) significantly reduces prevalence, reach, and exposure to illegal content, while the longer delays measured by the audit fail to reduce its spread. Though the link between delay and spread is intuitive, our simulations quantify exactly how takedown speed shapes exposure to illegal content. Building on these results, we point to the benefits of faster content removal to effectively curb the spread of illegal content, while also considering the limitations of strict enforcement policies.

翻译：社交媒体上的非法内容对社会构成严重危害，需要及时予以移除。然而，内容移除速度对非法内容的普遍性、触及范围和用户暴露程度的影响仍未得到充分探究。本研究通过对欧盟《数字服务法》透明度数据库中的数据（涵盖五大主要平台为期一年的记录）进行系统性审计，以考察内容下架延迟与上述影响之间的关系。我们发现，不同内容的下架延迟存在显著差异，部分内容在平台上存留数周甚至数月。为评估这些延迟如何影响非法内容的普遍性、触及范围及用户暴露程度，我们开发了一个基于智能体的模型，并利用实证数据对其进行校准。通过模拟非法内容的扩散过程，我们发现快速下架（数小时内）能显著降低非法内容的普遍性、触及范围和用户暴露程度，而审计所测得的较长延迟则未能有效遏制其传播。尽管延迟与传播之间的联系具有直观性，但我们的模拟精确量化了下架速度如何塑造用户对非法内容的暴露程度。基于这些结果，我们指出了加快内容移除速度对有效遏制非法内容传播的益处，同时也考虑了严格执法政策的局限性。