Modern authentication systems face a complex challenge in balancing security and scalability due to the computational intensity of hashing passwords with expensive algorithms. Ensuring secure authentication requires managing the work factor, or the number of hashing iterations, to withstand potential attacks while avoiding performance degradation. As computing power increases, systems must be updated to maintain secure hashing standards, as recommended by OWASP. Additionally, distributed systems can become inefficiently "chatty" when numerous services redundantly verify authentication, leading to increased latency and hardware costs. Compliance with standards like SOC 2 often necessitates additional security features such as two-factor authentication, which can further impact scalability by increasing network demand. Lastly, authentication systems must ensure high availability to prevent application downtime, which involves investing in more robust infrastructure.