If you choose to walk this path, do so with eyes wide open: verify checksums, create full backups, and always keep a recovery USB nearby. For everyone else, legitimate tweaking tools or simple Windows optimizations will provide 80% of the benefit with none of the anxiety.
If you are hesitant about using a repack, you can achieve similar results through official tools:
Modified installers can sometimes lack essential components, leading to system errors or registry issues.