For a blazingly fast application, optimizing Redis is key, but it's not the only factor. Redis performance can be hindered by a range of issues, including an imbalance of write over read operations, insufficient memory leading to OOM errors, low CPU allocation, various sources of latency (network, slow commands, persistence I/O, THP), character set mismatches with other databases, "hot" or "big" keys causing contention, hitting the maxclients limit, network bandwidth saturation, and improper client-side configurations or replication lag in clustered setups.