Memory Manager (Pro; Root)
As of FE Pro V4.1.4, a new tool was added to FE. This requires the Pro plugin and root access on your device.
Every app that runs, Android puts into an "out of memory group" based on their priority; FOREGROUND_APP, VISIBLE_APP, SECONDARY_SERVER, HIDDEN_APP, CONTENT_PROVIDER, and EMPTY_APP.
When Android needs memory, it starts killing off applications in these groups based on how much memory is free; starting with the group with the highest value.
For example, if you set HIDDEN_APP = 24mb; when free memory on your device dips below 24mb, Android will kill off apps running in this group. If the next highest value was EMPTY_APP = 20mb, then Android will wait until free memory hits 20mb, then start killing off apps in THAT group - and so on.
You can control the behavior of Android's "task killer" by setting these values yourself using FE's Memory Manager. FE's team has come up with sets of values based on common behaviors of users. These "presets" can be used without any knowledge by the end user - just pick the one that suits you and you're done.
If you're a more advanced user, you may want to "dial in" these values yourself instead of using one of the pre-built settings. To do this, you'll need to understand each of the groups and what apps get put in there.
Foreground Application - An app that you currently see on the screen. (also includes System and Phone)
Visible Application - An app that is visible to the user but not at the front, possibly because of transparency, etc.
Secondary Server - These are BACKGROUND applications and services. This typically includes launchers (Launcher Pro, etc.) and UI shells (Sense, Motoblur, etc)
Hidden Application - Apps that are not visible but still run in the background.
Content Provider - Processes that provide for other apps (Contacts, Calendar, etc.)
Empty Application - Apps that are paused and not doing any work.
As for it being safe, I presume so because such a well known application "company" wouldn't put out risky stuff and the Chinese normally know what they are doing. That being said, I doubt it is needed. But give it a whirl and see for yourself
PS this should really be in the normal Android section somewhere rather than a device forum. Maybe get more opinions/views over there (the whole of xda has reason to go there, not just particular device) and perhaps worth pm'ing a mod to get this thread moved.