With that many entries to deal with, you may be able to manage them through the Bulk Edit function. Click on the box to the left of a transaction and the Bulk Ignore / Bulk Edit functions become visible.
Enter 'stake' in the Search box and the staking entries should become visible.
Unclick the box to the left of the transactions and click on the funnel to the right of the Search box to find another way to search the data.