Crystal Reports Verify Database

I have a series of report where ALL 500 of the tables were brought over in the initial building of the reports. The user who built these never got any training. So instead of the reports being efficient they are painfully slow. The problem is we just converted all the reports to the SQL version a much faster reporting database and all the old unneeded tables we are not using or needing came over with the report. We found after mapping the old tables to the new SQL version of the reports made the reports run faster. If we removed the redundant or unused tables from the reports they ran even faster. We want to remove the unused tables.

However when we do this we
1. disconnect the mapped network drive to the report
2. go to the design view of the report
3. click on Verify database under the Database menu.
4. either click with mouse or hold down the Enter key to remove all unnecessary reports

When I notice sometimes ALL 500 tables can be removed in a matter of 2 minutes. Other times the report takes literally an hour plus to remove all the tables. I have watched the Task Managers  CPU spike for several seconds from 10% to 100% for every table removed. In some cases the CPU stays spiked at 100% for minutes. Thus causing my removal of the tables to be painfully slow.

Does anyone know what causes this or knows what can be done about it. Please advise. thank you.