I have a couple of macros that sort through db output and delete
unwanted information

Example:
Do while selection < ""
if selection 100 hours then
selection.entirerow.delete
else offset to next row
endif
loop

Two questions:

First, is there a faster way to do this, i.e. sort for greater than 100
and delete the results?

Second, on one sheet that only has three columns this runs very fast.
(28k rows in about 15 minutes) but on another sheet with about 35
columns it only does about 2 rows a second. What is causing such a vast
difference in speed? Is it the number of columns deleted during the
entirerow.delete line?

Thanks for the help.