Performance with hidden column

Hi we are in sem 3.5. In the planning layout after upgrading service pack 23 from 22, revised baseline in the forecasting tab was not giving the correct proportion. We tried to correct this but couldnot find a solution. Now we have changed the sequence for fiscal year in transaction upx_mntn1 to hidden, in column.(earlier it was filter) which solved our problem. But the effect is that it has doubled the number of columns(an additional column is coming with each column) though these columns are not visible in the forecasting tab.Now, we are not sure what will be the impact on performance. Can anyone please guide us.....