What's so bad about have a lot of volatile functions, provided you don't change them?

Hypothetically speaking, suppose if I were to have a worksheet with over 10,000 cells with index(indirect(range1),match(date,indirect(range2),0)). Ranges 1 and 2 are determined by the number of date entries. They are unlikely to change, only when new date entries are added because new increased row numbers.

Ie.
A1 = Jan 1, 2014 B1 = food
...
A20 = Feb 4, 2014 B20 = chocolate

A reference cell at C1 = row(max(A:A)) = 20 (to find max row number)

In a separate worksheet, I want to reference items from column B, based on date entry in column A.
I retrieve the data in the operation below:

=index(indirect("Sheet1!$B$1:"&'Sheet1'!$C$1",match(date here,indirect("Sheet1!A1:"&'Sheet!A'$C$1),0))
(by the way, am I writing this correctly?)

Far into a month ahead or something, suppose I add new date entry in column A, making C1 = 21 now.

Now, suppose I multiply this type of operation across over 10,000 cells. What's wrong with this? What problems can I face?