help me in reducing ram usage of excel file

i have a .xlsb excel file sizes 1.4mb,
when i open it, it takes 1.9 GB of ram.
so i found solution that switching forcefullcalculation to true, and it worked.
after switching, it only consumed about 20mb of ram. (200? it dosen't matter)
so i saved the file and when i reopened it(after exiting excel), the amount of memory consumed was 1.9GB again..
and i checked the workbook attribute forcefullcalculation, it was true.
I manipulated it in 2 ways
1. i switched it to false, memory was same 1.9GB and switched to true again, became 20(200?) mb..
2. i set it to true again, memory became 20(200?)mb again.

i don't know why forcefullcalculation attr do not work when opening excel file.

plz someone help me i can send you my file.