CCleaner is a powerful tool for optimizing system performance by cleaning junk files, fixing registry problems, and controlling startup items. Offers a deep clean for cache, temp files, browser history, restore points, duplicates, and other unnecessary files. CCleaner provides a registry cleaner, program uninstaller, and free space eraser. Ideal for users looking to optimize system performance. Had a past malware incident, but current versions are considered secure if kept updated.