SQL & PL/SQL :: Columns With NULL Values?

We are working on a migration project and we need to move 75 million rows from source system to target system.

Total number of columns in source system - 90 cols.

Out of the 90 columns 10 cols are system fields and rest 80 are properties for each record.

We are required to migrate all system cols and some required properties. In total we will migrate around 25 columns[10+15] for each record.

Before actaul migration , we need to do a data cleansing activity and hence we move the data to a staging table.

To create the staging table, we considered the below appraoches.

1. Create the staging table with around 30 coloumns so as to fit the data from source system[map the columns based on datatype]

2.Create the staging table with actual columns[90 columns] and import only the required properties. The rest all columns will remain NULL.

Do the data cleansing and move to target system.

My question here is, if we go with approach 2, We will not mix the data, as there will be a one-to-one mapping. But many columns will not have data and remain NULL. Will it affect the performance since we deal with 75 million rows.