Formula vs. Variable: which is the best way to code mathematic conditions inside IF statement when looking for computation time?

Hi,

I have a very long calculation (several days...) based on many iterations over if-conditons. Most times the conditions are not true so everything else is skipped, so that the if-condition itself seems to be the bottleneck of the computation time. I am wondering where it makes sense for the computation time to do a calculation directly inside the if-conditions and where not:

Example without reuse of Variable:

if sum(Values(Cond))/sum(Durations(Cond)) >= Threshold1

vs.

ConditionedValues = Values(Cond)

if sum(ConditionedValues)/sum(Durations(Cond)) >= Threshold1

Example with reuse:

if sum(Values(Cond))/sum(Durations(Cond)) >= Threshold1 && max(Values(Cond))/sum(Values(Cond)) <= Threshold2

vs.

ConditionedValues = Values(Cond)

if sum(ConditionedValues)/sum(Durations(Cond)) >= Threshold1 && max(ConditionedValues)/sum(ConditionedValues) <= Threshold2

Obviously I suspect that in the first example it should be (slightly?) faster without a variable? If so, by how much are we talking?

And in the second case I suppose it depends how often the first condition is met as only then I jump in the second condition and take profit of the reuse?

Is there a rule of thump or a way to predict the performance without doing the full calculation twice and timing it?

Thanks in Advance!

Best Regards

Seb