Creating a new object is never free, but it used to be far more expensive. To my knowledge the original Java GCs weren't compacting & had to find the best place in the heap to stick a new object. This required a linear search of the available free blocks. This is obviously much slower than incrementing a pointer at the edge of your used space. Unfortunately my search-fu has failed me & I can't find corroboration of my claim.

My impression of Java these days is to start with the "right" thing (allocate as needed, etc) and not to overly concern yourself with performance until it becomes an issue. There are certainly situations where allocating lots of objects (say billions or, maybe, millions) causes performance issues, but creating object pools to preemptively avoid that is a lot of extra work that may not be worth it.

Short answer: not necessarily

A good JVM contains optimizations, which makes it cheap. For example, it will try to allocate the object on the stack instead of the heap. Apart from field initialization, this costs nothing, because the stack pointer probably had to be changed anyways.