Anti-virus software protects systems from malware like viruses, worms, and spyware, and removes any existing malware to improve performance and prevent data loss. Backup software creates copies of data to allow restoration in case of system failure or data loss, improving security. Disk cleaners and defragmenters free up storage space by removing unnecessary files and organizing files, improving system performance. Formatting drives removes all existing data, allowing space for new data and potentially improved performance. Firewalls provide security without necessarily improving performance, while utilities like internet histories do not significantly change performance.