I have a very large workbook with many worksheets and am experiencing bloat
and slowness. I know, I know, I am inviting joke responses about using
Gas-X, but please restrain yourselves!

In order to provide a visual key as to which fields are empty, I am using
conditional formatting to turn empty fields red. I also use Data Validation
to control what goes into the cells.

I never know how many rows will be filled in, so I just select the entire
column and put in conditional formatting and the data validation, and then
delete the conditional formatting and data validation for the header row.

Am I causing bloat? Is the conditional format and data validation being
recorded for every one of the 65000+ cells in a column, or are they just
stored in one place and the program applies it appropriately as needed.

In addition, am I causing slowness in recaluclation or movement through the
sheet?

Or is the bloat and slowness just because of the amount of data involved?

I have relatively few formulas, but I do have lots of dropdowns that draw
their options from lists on a hidden sheet.

My tests have been inconclusive. I also have been working on this workbook
for several years. Is there some sort of "compaction" I should apply to it?