Go's Surprising Memory Allocation Trap: A 30% Regression Story

A seemingly innocuous refactoring in a Go project led to a 30% performance regression. The culprit was the `GetBytes` method of the `ImmutableValue` struct, which used a value receiver, causing a heap allocation on every call. Heap allocations are significantly more expensive than stack allocations. The root cause was the Go compiler's escape analysis being imprecise; it failed to recognize that the value receiver wouldn't escape. Switching to a pointer receiver fixed the problem. This case highlights the importance of understanding the Go compiler's memory allocation decisions and using appropriate receiver types for high-performance Go code.