Yellow Booster is a free app from Yellow Apps Team, which also provides the battery tool Yellow Battery. This Yellow app aims to speed up your phone or tablet and cool it down through various means: from getting rid of files neither you nor your phone care about, to monitoring your processor's current heat levels and providing a bevy of options to reduce power consumption and cool it down, this app provides a speed-boosting toolbox.
Learning about the details
The most basic function of Yellow Booster is cleaning up junk files. It does this by looking through folders, such as temporary storage folders, which are not used, or by getting rid of APKs from apps you've already installed, among other methods. This frees up space, and can often serve to "defragment" your internal storage, making launching apps faster. If that doesn't do the trick, you can have Yellow optimize specific apps, as well.
All of these functions are buttressed by a "whitelist" function: you can specify folders where Yellow should not venture, and allow apps to eat away at the CPU when otherwise the app would restrict them. This gives you control over how optimized your phone is, in case another app *needs* to run at startup or something similar.
Everyday utility dressed up
With a name like "Yellow Booster", it should come as no surprise that the app is very, very yellow from the moment you start it. Fortunately, it uses fairly dulcet tones of yellow, and combines them with white in a fairly austere but nonetheless attractive user interface. As functionality goes, the app is easy to navigate: although at first blush it may be hard for a novice user to understand what each screen does, the app does everything it can to help, and in any case, there's enough safeguards and clarity to be found that it's comfortable to use, even when the app digs deep into your phone.
Of course, while the interface is great and the app provides a lot of simple functions to speed up your system, there is one catch. The app promises to help cool off your CPU, as well as your device itself, improving performance, increasing your device's lifespan, and helping your fingers out, as well. The problem is that since heat directly correlates to processor usage, this may not work: if the apps you run or the things you do simply tax your phone, Yellow has a chance to help you, but offers no guarantees.
Breaking it down
Yellow Booster can't solve every possible problem with your smartphone or tablet. If your device of choice is old enough, any slowness you experience might be related to the power that modern apps to demand. But equally, the older your device, the more likely it is that you can benefit from cleaning up junk files or paring down the number of apps that run in the background. Booster can do these things admirably, and it's for that reason that it's worth considering.