What does this mean "Time vector is 90 sec"? All we know is it has 100 elements, and we don't even know what the units are.
The loop will go as fast as it can. The loop as you have it there will probably get done within a few nanoseconds or microseconds. Not sure if you were thinking that loop would take around 90 seconds or more, but it won't unless you have a lot more time consuming stuff in there that you have not shown.
If you have any more questions, then attach your data and code to read it in with the paperclip icon after you read this:
save('camsi answers.mat', 'Time', 'X', 'Y_C');