Performance difference between MOVE and = assignment in ABAP

No, that is just the same operation expressed in two different ways. Nothing to gain there. If you're out for generic hints, there's a good book available that I'd recommend studying in detail. If you have to optimize a specific program, use the tracing tools (transaction SAT in sufficiently current releases).

The two statements are equivalent:

" To assign the value of a data object source to a variable destination, use the following statement:

MOVE source TO destination.

or the equivalent statement

destination = source.

"