Is there any upper limitation of "Evaluations Maximum Array Size" ?
Is there any relation of it and physical memory and is there any demerit of increasing this parameter in case of more fewer elements selected (eg.it takes much more time to solve and so on)?
The Maximum Array Size is used to allocate the main static array of memory that is used for Response Dynamics.
Some of the memory usage has been converted to dynamic memory to help alleviate problems with the static memory array usage.
It is somewhat aligned with the physical memory. As long as you haven't requested a larger Maximum Array Size than the physical memory available, you should not see any degradation of performance when using fewer elements for the evaluation.