Navigating the NIST PQC Standards: Trade-offs and Case Studies

The rapid advancement of quantum computing poses a significant threat to classical cryptographic systems, particularly to widely used public-key schemes that rely on integer factorisation and the discrete logarithm problem. To ensure long-term data security against potential quantum adversaries, post-quantum cryptography (PQC) is currently standardised by the National Institute of Standards and Technology (NIST). This paper goes beyond a theoretical overview by employing a systematic methodology to evaluate the empirical performance trade-offs of the newly standardised algorithms (ML-KEM, ML-DSA, and SLH-DSA) and key finalists (FN-DSA and HQC). Based on a comprehensive review of fragmented performance data, the work presents a comparative analysis focusing on data overhead, computational latency, and resource efficiency. As a primary contribution, this study proposes a deployment-oriented taxonomy that explicitly maps these PQC standards to optimal practical use cases, considering diverse constraints across Internet of Things, cloud environments, and blockchain networks. Furthermore, the paper addresses critical real-world deployment challenges, such as vulnerabilities to side-channel attacks and hardware-level implementation constraints. Ultimately, this work systematises current knowledge into a unified decision-making framework, guiding system architects in complex migration towards a quantum-resilient digital ecosystem.