Be strategic about memory allocations to improve performance in your C++ code. Consider two key optimization patterns: 1. **Pre-reserve container capacity**: When using containers like vectors that will grow to a predictable size, use `reserve()` with a reasonable initial capacity to reduce allocation overhead. This prevents multiple small reallocations as the container grows. ```cpp // Before - May cause multiple reallocations during population vec_rules[i].resize(n_rules); // After - Pre-allocate with reasonable capacity vec_rules[i].reserve(16); // Start with reasonable capacity ``` 2. **Avoid unnecessary preallocation**: When designing functions that return variable-sized data, prefer return values over output parameters when the required size is difficult to predict in advance. This eliminates the need for callers to pre-allocate buffers of the correct size. ```cpp // Before - Requires caller to pre-allocate buffer of correct size int schema_to_grammar(const char *json_schema, char *grammar, size_t max_len); // After - Return value approach avoids pre-allocation issues std::string schema_to_grammar(const char *json_schema); ``` Both strategies help minimize memory churn, reduce fragmentation, and improve overall application performance, particularly in performance-critical code paths.