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You can overclock your phone, flashing an overclocked kernel
Your phone is smoother when it has less processes active in background and when you have more free ram.
If you have root you can use greenify and hibernate easily a lot of apps
If you mean you want to stay close to stock Roms, there are mod20c and CleanRom. There are debloated, rooted, fine tuned stock roms. mod20c has default launcher but no stock browser. Quite the opposite, CleanRom has stock browser but no stock lg launcher
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