GA optimization running endlessly

I have been trying to use the Genetic Algorithm to find the lowerest point in of an output over a range of value (variable i) in simulink. Please note that variable i is feed into 3 different blocks (all normalised).

Attached in my matlab code:

function[Mdot]=FYPoptver1()

v=linspace(0,1,3);

i=[t,v]; % i is a range of input into the simulink model

lb = [0];

ub = [1];

rng default % For reproducibility

options = simset('SrcWorkspace','base','ReturnWorkspaceOutputs','on','DstWorkspace','current');

Mdot=sim('FYPver6',380); %Simulink model, time final

[fuelburn,fval] = ga(@FYPoptver1,1,lb,ub) %not quite sure if nvars = 1 but only but i assume as there is only input i in the simulink model hence 1

end

As the simulation is seemingly taking endless time, my guess is its probably because there are 4 'to workspace' in the simulink model. Is there any way to specify the exact output to find the lowest value? If not, is there anything else that I can do/done wrongly?

I have also read this discussion (below) that suggest that GA might not the right tool to use in this case. If so, I only have 1 more question, how do I set the condition where the solver will stop?

https://www.mathworks.com/matlabcentral/answers/387958-why-is-ga-optimization-ridiculously-slow-to-solve-a-problem