title: Why should I use placement new?
body: <p>As it seems, <code>placement new</code> creates a new object on a preallocated memory, so does it mean that it would take less time? Looks like it's faster then allocating using the old ordinary <code>new</code>. Then, if this is so convenient and faster, why not use <code>placement new</code> all the time?</p>