As a quick refresher, fetch is a synonym for fetchrow_arrayref, which in general will be faster than a fetchrow_array because it doesn't have to allocate more memory and assign more variables.

In ColtsFoot's case, I think variable allocation might be part of the problem if dealing with Memo fields. Try checking the result of fetchrow_array for errors; the best way to do that is to turn on RaiseError and PrintError.

You might also want to look at bind_columns, which gives the convenience of variables without the pain of re-assigning them for each row.