I'm unfamiliar with Tigerlilly.
RAM cleaners are generally best avoided. When an app is first opened it's loaded from storage into memory (RAM) for quick access. When you clear your RAM (or that specific app from RAM), it has to load all over again from storage. That takes more time, processing power, and battery. If the phone needs to free up RAM for new apps, it'll close others down all on its own.
If useless/redundant/bloat apps are running in the background, freeze them. If you're rooted you can uninstall system apps, but It's better to freeze (disable) them than uninstall them. The phone might glitch out and you can always unfreeze them. Besides, deleting system apps does not free up any usable space as the system partition is a set size and is unusable for stuff like pictures or music.
Look into Greenify. Without root access it basically works as a RAM cleaner that automatically shuts down specified apps after closing. With root access it can prevent specific apps from loading until you want them to. Of course, there's a white list that you can add apps to that you don't want removed from running in the background.
I don't have my Galaxy Light anymore. Like you, I got completely frustrated with it. 30 seconds to load the damn dialer, 2 minutes to load the wifi hotspot, etc. Unlike you (so far, anyway), I hulk-smashed the POS into oblivion after a bit too much to drink.
When I bought my Galaxy Light it was the best one I could afford at that time (having switched from Verizon and paying way too much per month). Soon after I got my hands on a Nexus 4 and used that as my primary device, but still used the Light as my "phone" and internet mule (USB tether and wifi hotspot). I liked the Light for its small size (since I carried both phones), but after time it got less and less usable. I don't know if it was because I was running too many Xposed mods, or if I simply wore it out from use/abuse.
Do a factory reset (re-root if necessary), freeze/disable bloat and redundant/useless Samsung apps, and use Greenify to keep apps you don't need constantly running out of your RAM. Also, be sure to turn off S-Voice. Double tap the home button, load S-Voice, and then go into its settings and turn it off. S-Voice lags the phone because when you hit the home button it's waiting to see if you hit it again. Turn it off, and it won't lag from waiting.