I wrote some Worksheet_SelectionChange code to augment a large workbook
in use by our company. The routines are not complicated, and just take
care of some routine housekeeping-type chores. The code runs when the
cell pointer lands in a certain cell range; when I explained this
functionality, the guy in charge of version control for this workbook
questioned whether the routines would sponge up excessive system
resources.

Do these routines take up extra processor time, or memory allocation,
or contribute substantially to "overhead" that may cause the
spreadsheet to operate more slowly than it might without the code?

Thanks