Make faster calculation

Hi All,

I have a Excel template for my Humidity and Temperature reading
With the help of the forum expert (Vikas_Gautam) http://www.excelforum.com/members/575994.html
I achieved what I want but my computer is so slow.

Is there any method that makes the calculation faster? because if I will apply it to my datasheet that containing
20 sensors my computer takes time to calculate the given data.

Please find the attached template.

Thank you.