After the clarification about the template issue, I tried to remove the map and decided to use the template instead. It removes the needs to find which pool I have to allocate (due to map), which increases the performance slightly (up to 0.1 sec) compare to the one that uses map and without template. If I reserve the capacity (by the total number of the test), it is reduced to 0.23 sec! The number of classes that would need this would probably at hundreds or less, unless doing such template that way is very expensive (I don't know).
EDIT: As Waterlimon suggested, I've changed the benchmark against the Car class to be quite a bit the same as Entity. The Car class now inherits Vehicle, where it has to pass a string through its constructor and save it to a name variable. Apparently this is the culprit. Now the Car increases up to 0.5x seconds!
Now everything looks quite normal, as a matter of fact, better!
Thanks a bunch guys!! you guys are very helpful.