What's the best Android app for cleaning residual files and speeding up a sluggish phone?

Smart Cleaner：Phone Clean Tool is a utility app that addresses common performance issues by focusing on residual files and system optimization. Residual files, such as temporary data from uninstalled applications or outdated caches, can accumulate over time and slow down device operation. This app scans for these remnants and allows users to safely delete them, which often results in regained storage space and smoother performance. Key features include a deep clean mode that identifies rarely accessed files, a one-tap boost function to halt background processes, and a storage analyzer that categorizes data by type. For instance, after uninstalling several apps, the tool can detect and remove associated folders that other cleaners might miss. Reviews indicate that users experience noticeable speed improvements, particularly on older devices where storage clutter is more prevalent. However, some feedback points to occasional ads in the free version, which may interrupt the workflow. Despite this, the app's straightforward interface and regular update schedule make it a practical option for maintaining phone health without technical expertise.