Each virtualizer has his strength and choosing the one which will be the perfect fit depends on the context. In most cases the swap file virtualizer is faster than the JRFileVirtualizer. The difference comes from file system implementations, most deal better with one large file than with many small files. But the only catch is that you need to pick sensible parameters for the swap file. Good default values are something like 4096 for block size and 200 for grow count.