Should the same process (like shifting cells to the right) take significantly longer to complete each time it is run?

For example, the first time, the process takes 8 seconds; the second time, 20 seconds; the third time, 80 seconds; the fourth time 160 seconds; the fifth time; 6 minutes; etc.

My spreadsheet has 9 columns and 51,000 rows and it contains no macros and no formulas.