[germainebull]

Is it realistic to construct a computer with optimal capabilities that is the size of my palm?

What is the smallest size of a computer that bears all standard capabilities?

[Fergal]

Is it realistic to construct a computer with optimal capabilities that is the size of my palm?

The answer to that would depend on how you define "optimal capabilities". However, modern smartphones are powerful computers and could fit in the palm of your hand, so in my opinion the answer is yes.