Avoid multiple passes through the same data structure when a single iteration can accomplish the same work. This reduces computational complexity and improves performance, especially for large datasets. Instead of using multiple array traversals like `filter_map` chains: ```ruby # Inefficient: multiple traversals params = uris.filter_map { |uri| uri_to_local_account_params(uri) } usernames = params.filter_map { |param, value| value.downcase if param == :username } ids = params.filter_map { |param, value| value if param == :id } ``` Use a single iteration to collect all needed data: ```ruby # Efficient: single traversal usernames = [] ids = [] uris.each do |uri| param, value = uri_to_local_account_params(uri) usernames << value.downcase if param == :username ids << value if param == :id end ``` This principle also applies to avoiding duplicate iteration logic in collection processing services and preventing redundant recursive operations by checking if work has already been completed before proceeding.