Rust's collect::<Vec<_>>() memory leak footgun

Interesting discovery about Rust 1.76’s collect() optimization. When converting a vector of larger elements into smaller ones (e.g., 128-bit to 32-bit), the new vector reuses the original’s memory allocation, tripling capacity unnecessarily.

Solutions:

• Call shrink_to_fit() after collecting
• Use Box<[T]> for fixed-length collections
• Consider arena allocation patterns