The reason why not all applications use multiple threads is that developing multiple threads is likely to be difficult. Writing many content applications correctly requires time, effort, and a lot of energy. Even when completed, many applications show no improvement.Often, any application that spends most of its time waiting for user input comes with a kernel that is fine. Sometimes programs do not support multi-core CPUs because the programming logic needed to implement multi-core support can make the application more vulnerable.I would think that 'weak' in this context means more prone to freezing and falling.This seems to be a programming problem. To use multiple cores, the application must be built from the beginning so that it can be used correctly. Some programming languages ​​are better at providing this feature than others, but they require you to think differently about how you program.