According my unscientific tests, it is about over 100 times faster. On my laptop I can throw one million exceptions in 15ms millisecond, when reusing the same exception objects, compared to 2 seconds when creating a new exception object every time with a quite shallow stack.

When a new exception object is created, the slowest operation is filling information about the stack trace. It is possible to override Exception's fillInStackTrace() with an empty implementation. In this case throwing exceptions with new exception objects, is only slightly slower than using one exception object (17ms vs 15ms for 1M throws).

Deeper stacks make difference even bigger. Adding 100 nested invocations to the stack slow downs the classic approach (a new exception object created just before invocation) to 9 seconds, while alternative approaches are not affected.