1. A method for reducing latency associated with accessing content of a memory page that has been previously swapped out by a guest operating system in a virtualized computer system, comprising: identifying content of the memory page that has been previously swapped out by the guest operating system to a swap file; prefetching the identified content in the guest operating system's swap file; caching the prefetched content in a prefetch cache in host machine memory; detecting an I/O read command which is associated with the cached content and issued by the guest operating system; and providing the cached content from the prefetch cache, thereby avoiding accessing the guest operating system's swap file.