[esailija]

Since this is usually downplayed because the "code is shared", to be more specific, for example in V8 in x64 (node.js, Google Chrome), the theoretical minimum memory used by a function object is 72 bytes:

- Map pointer: 8

- Properties pointer: 8

- Elements pointer: 8

- Code entry pointer: 8

- Initial Map/prototype pointer: 8

- SharedFunctionInfo pointer: 8

- Context pointer: 8

- Literals/Bindings pointer: 8

- Weak fields pointer: 8

So if you have a Person class with 30 methods, the methods are taking 30 * 72 = 2160 bytes at the very least. The actual data for a person might take 200 bytes, if we store e.g. full name, age and address so in this case there is like 10x overhead. If you print the details of 200 people per page request and there are 100 people connecting to your server, you are wasting 200 * 100 * 2160 =~ 40 megabytes on memory on storing all these useless function objects at that moment. That is just crazy.

And in GC language it's never just memory, a GC will eat exponentinally more CPU time when the amount of memory you use reaches closer and closer to limits.