The Proxy pattern's main downsides are the extra layer of indirection it introduces, which can add complexity and performance overhead, and the risk of misuse when it's applied in situations that don't actually need access control or lazy behavior.
Key Points: • Adds an extra class and call hop between the client and the real object, making debugging and tracing harder. • Can introduce performance overhead from the additional logic executed on every call through the proxy. • Overuse leads to design clutter, with proxies wrapping objects that don't need any special access handling. • Bugs in the proxy's delegation logic can silently mask or alter the real object's behavior. • Some proxy types, like dynamic proxies, add reflection-based overhead and reduce compile-time type safety.
Example: Wrapping every simple data class in a proxy "just in case" adds indirection with no real benefit, whereas the overhead is justified for something like a remote proxy that genuinely needs to manage network calls.
Interview Tip: A concise interview answer is:
"The main downsides of Proxy are the added indirection and potential performance overhead from routing every call through an extra layer, plus the risk of over-applying it to simple cases that don't actually need lazy loading, access control, or remote communication."