为什么进程的内存分配缓慢，它能更快?

I relatively familiar how virtual memory works. All process memory is divided into pages and every page of the virtual memory maps to a page in real memory or a page in swap file or it can be a new page which means that physical page is still not allocated. OS maps new pages to real memory on demand, not when an application asks for memory with I relatively familiar how virtual memory works.