Call A:
double Value = Object.Object.Object.Object.DoubleValue;
Call B:
double Value : Object.DoubleValue;
If this were in a for loop and being called many times over and over would there be a performance loss for calling an object within an object or is it worth noting about?
Readbility is for programmers, optimizations are for compilers (and jit optimizations, to be honest).
Do whatever is the standard in your team and is more readable.
If after you do it you suspect some performance issue – use a profiler to check if it is indeed the case, and do adjustments accordingly.