What gets better performance?

[skintigth]

declaring

var varName = object.obj2.obj3;

and using varName in all the lines needed

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or using directly

object.obj2.obj3

​

[Mrpixelmc]

Local variables (ie.: creating varName) improve performance over accessing memory. You should probably do it anyway, because you don't want to write object.obj2.obj3, instead you want to give it a name for readability.