>>>It goes without saying that (1) only the class definition is kept in memory (2) the object properties are not shared. Properties have to be initialized each time
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>>I agree. I thought so too as property values are different (or could be different) for all instances of the class.
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>But then it's only properties with nondefault values. The rest are looked up in the class definition (or parent class, if at default) when needed.
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>(Of course, I do not really know this; I think I read it somewhere once upon a time, or more than once,but can't remember where)

Good point. BTW, if the properties are left as default, are they read each time or only once?