Speaking more of the same, it makes no difference. The explanation is in the other answers.
A practical point to be aware of is how these classes are loaded.
You will probably want to use an autoloader. Then yes, in this case will consume processes that greatly influence performance.
An autloader is to include a file when it invokes a class that is not present in the body of the script. This process of including the file consumes a lot of memory and processing.
To reduce this cost, it is recommended to create build cache structures. We can also choose or reinforce with cache libraries like Memcache, APC, Opcode, among others.
However, if the concern is whether the use of OOP classes or concepts will make the system less performatic than writing the codes in procedural style, obviously, the procedural style is much faster. However, think this way, you need to go from your home to the corner bar that is 20 meters away. How will you go?
1. a pé
2. de moto
3. de lamborguini
I’ll believe you chose option 1.
Now, let’s say you want to go from your home to Paris.
1. a pé e segue nadando pelo oceano
2. de moto e segue de barco a remo pelo oceano
3. vai até um aeroporto e segue de avião
I think you opted for the plane.
But why is a plane that consumes much more resources and is heavy? Can’t you still walk and continue swimming in the ocean? After all, it gives the same result.
Think of this analogy or similar analogies and you will understand when to use a style or conceitY.
Always think about the ultimate goal. What cost/benefit option X or Y will generate?
Analyzed cost/benefit, think about effectiveness.
The cost/benefit is effective?
These are basic steps to make a more appropriate choice.
The number of classes does not influence no, the instances are that occupy memory and the algorithms processors.
– Ricardo