What is the purpose of swapping in virtual memory?

Question

also please explain Virtual Memory Can Slow Down Performance why and how?

Answer 1

When the processes running on server / instance attempt to allocate more memory than your system has available, the kernel begins to swap memory pages to and from the disk.

This is done in order to free up sufficient physical memory to meet the RAM allocation requirements of the requester.

Virtual Memory swapping is an “expensive” activity in terms of its impact on overall system performance. If processes on your system regularly attempt to allocate more than the available physical RAM, you may experience drastic increases in web site response times and loss of execution speed.

Unfortunately only two solutions exist - either optimize your applications to utilize memory more efficiently, or add more physical RAM to the system.