You would avoid instantiating an object from a class when you need to utilise static methods or attributes that do not require the state of an object to be utilised. Static methods belong to the class itself, not to any particular object, and can be called without creating an instance of the class. Additionally, you might avoid instantiation when creating an object is resource-intensive, and the situation does not necessitate a separate instance, such as when a single shared resource can be used. Another scenario is when employing design patterns like Singleton, where the class design restricts object creation to ensure that only one instance of the class exists throughout the application.

Garbage collection is a form of automatic memory management that reclaims memory occupied by objects that are no longer in use by a program. When an object is instantiated, it occupies a portion of memory. However, when it is no longer needed—typically when there are no references to it—the garbage collector will eventually free up this memory. This process is crucial as it prevents memory leaks, which can cause programs to use increasing amounts of memory over time, leading to reduced performance or even application crashes. The garbage collector operates in the background, identifying objects that are unreachable by any references in the program and then deallocating their memory.

'Pass-by-value' refers to the method of passing the value of a variable to a function as opposed to a reference to the variable itself. When related to object instantiation, it means that when objects are passed to methods, any modifications made within those methods do not affect the original object but rather a copy of it. This is particularly important when objects contain data that should not be altered unintentionally. In pass-by-value, the called method receives a copy of the object's data, and thus, the original object's state is preserved. It ensures that the original object remains unchanged outside the method, which is crucial for maintaining data integrity in a program.

A constructor in object instantiation serves as a special method that is automatically called when a new object is created. Its primary role is to initialise the new object's state by assigning initial values to its attributes. In essence, the constructor sets up the conditions for the object to operate correctly when it is first used. For example, if a class defines an object's colour and brand, the constructor ensures that every new object instantiated has specific values for these attributes. This process is vital because it allows objects to have distinct properties right from the beginning, promoting diversity in the attributes of various instances of the same class.

Constructor overloads allow a class to have multiple constructors, each with a different set of parameters. This affects object instantiation by providing flexibility in the creation of objects, allowing different initial states for an object. For instance, one version of a constructor may only initialise a few attributes while another may require all attributes to be initialised. This enables the programmer to create objects with different sets of data from the same class. It also enhances the class's usability by allowing it to be versatile in different contexts. Overloading constructors can accommodate various instantiation needs while keeping the code clean and coherent.