[Android Software/Hacking General [Developers Only]] thetechnologician:
Use:

The Fly-On Mod App serves as a Graphical Interface to the now-famous Fly-On Mod script, which means that you no longer need to flash the latter through recovery since it will evantually be included in every new App release . However, as of the Alpha releases, only select scripts are supported. We now support all of the Fly-On Mod scripts.

How to:

EDIT: The app no longer needs any installable requisites : Just install the apk, toggle the wanted tweaks and click the "apply changes" button. Let the phone reboot and enjoy :D

Useful Info About Tweaks:

-Fly engine :

As of Beta2: Fly engine comes in 6 different scripts, every script is packed with some useful tweaks aimed to provide a lagfree experience while being battery friendly.

and thus Fly engine's tweaking target is your android's phone core(system+linux kernel), and here are some detailed info :

-Network tweaks : Used to improve overall network speed, by tweaking ipv4, netcore and TCP settings.

-Build.prop tweaks : as you all know the build.prop file is your android handset’s ‘ID card’, thus it controls many of your Android system's settings, tweaking those settings would greatly improve responsiveness as well as battery life.

-Disable sleepers : Disabling I/O scheduler sleepers would improve I/O smoothness.

-Sysctl tweaks : system control tweaks are used to tune virtual machine settings according to your device's RAM amount. Used with the Ram manager, the combo provides a lagfree experience.

-Kernel tweaks : as the name states.

-VM tweaks : more virtual machine tweaks( VM heap size tweak for now).

-I/O tweaks :

-R/W Turbo : Read/Write turbo script increases your SDcard's read-ahead speed, and contains some useful I/O tweaks.

-EXT4 tweak (For devices with EXT4 File system only) : Disables journalism which would improve File system performance.

Ram manager :

-LMK : The Low Memory Killer is a constant debate between more free RAM and more multitasking capabilities as free RAM is actually wasted RAM.

The Low Memory Killer is actually a feature in the Android OS used to improve memory management.

This is an important feature due to the perennial problem of having low free memory causing lagginess and slowness in launching apps. When you have free memory lingering around the number of 40MB or less, the Android OS just lags like hell.

What this would mean is, you would want to tweak the LMK to not have the situation of it having less than 100MB.

The modern Linux machine in the Android ecosystem relies on a mechanism called Low Memory Killer (LMK) to consistently free up RAM. This is due to Android's internal mechanism of caching apps (and never fully exiting them) when you press the back button. This is to enable faster app switching and provide a seamless experience for apps usage model. Android also, by itself will also constantly look for often used apps to cache them for faster app opening. This will happen even before your system fully boots.

Now, when you mention LMK, the most obvious thoughts that come up are minfrees and Out Of Memory (OOM) groupings. Yes, those two are integral parts when it comes to LMK. The issue here is that no one actually mentioned that there are two LMK systems in Android, that being:

+ Linux LMK

+ Android Dalvik VM LMK

-ZRAM : is a Linux kernel feature that provides a form of virtual memory compression. zram increases performance by avoiding paging to disk and using a compressed block device in RAM.

-KSM : Kernel same-page merging lets the system share identical memory pages amongst different processes. The result is obviously an improved multitasking experience.

-Killer : that's a script used to kill media seerver and google play services when battery draining wakelocks occur to improve battery life.

-Cleaner : Cleans /system and /data partitions by deleting many unuseful logs.

-Governor tweaks : Tunes your CPU's governor settings to provide a smoother, yet battery friendly experiece.

-Fstrim : Some Android users suffer from poor performance after some days/weeks of heavy usage. This is due to a well-known TRIM bug affecting these devices, so this lagfixer script is used to fix such a bug.

-Zipalign : is a tweak used to optimize Android application (.apk) files. The purpose is to ensure that all uncompressed data starts with a particular alignment relative to the start of the file. Specifically, it causes all uncompressed data within the .apk, such as images or raw files, to be aligned on 4-byte boundaries. This allows all portions to be accessed directly with mmap() even if they contain binary data with alignment restrictions. The benefit is a reduction in the amount of RAM consumed when running the application.

-SQlite optimizer : Vacuum and Reindex tweaks are used to optimize database of all apps in /data and /system, to achieve better performance.(expect longer boot time when this tweak is enabled)

-DNS caching : There are thousands of DNS servers on the internet, and your smartphone will be querying a lot of them. They start to "talk" to eachother to see if any server has information on the domain you are trying to access. Assuming the site has never been queried before, your request will eventually reach one of the nameservers (the primary source of the information), and the domain will be 'resolved', the IP identified, and your device now knows where the server is and can initiate communication; what about if your device already knows that server, it'll initiate communciation immediatly reducing the lag, that's what DNS caching is all about.

-Entropy engine : This engine can reduce lag by keeping a section of the Android file system (/dev/random) full of random bits so that the system does not have to wait for the file system to generate them.

OpenVPN : https://openvpn.net/