Fully homomorphic encryption (FHE) schemes offer the capability to perform arbitrary computations on encrypted data without the need for decryption, making them highly attractive for secure control applications. However, there are several challenges and limitations when applying FHE in real-time control scenarios. One major limitation is the computational overhead associated with FHE operations, which can significantly impact the control system's response time. The complexity of FHE algorithms can lead to increased latency, making them unsuitable for time-critical control applications. Moreover, the multiplicative depth and noise growth in FHE schemes can limit the types of computations that can be efficiently performed, posing challenges for complex control algorithms. Ensuring the scalability and efficiency of FHE implementations in real-time control applications remains a key challenge that needs to be addressed.