For example, I am playing a game named growtopia, and I realised that when I disable the music volume and sfx volume, my game become smooth, so does enabling the in-game music really affect lagness of the game?
Muting music in Growtopia shouldn't really affect lag, since the code for the music settings is made this way: You can turn the volume to any number between 0% and 100%, but that only determines how loud the music is. The music is always playing in the background, even if the volume is set to 0%.
The same thing applies to SFX.
If you want to avoid lag, though, I suggest turning the graphic detail option all the way down. That will affect lag since it's simplifying the code for rendering the background and other graphic aspects of the game, resulting in smoother gameplay.
In reply to this: I realised that when I disable the music volume and sfx volume, my game become smooth: correlation does not mean causality, that means the lag had to be affected by some other aspect.
In conclusion, no, turning the volume for everything down does not affect the lag.
It really depends on the specifications of your device and your internet speed. Growtopia does tend to lag and force you to disconnect often. I suggest turning down graphic settings if you are experiencing lag and inputting a command '/radio' to stop public broadcasts. Personally I keep the in-game music off, this shouldn't affect much in the way of lag.
Hopefully this helps.
No.not really.you will always have a little bit of lag...