Export data - export resultset to Excel takes very long time - why?

I am using TOAD for Oracle 10g – when I export a resultset to Excel, it can take up to 3 hours. The file size of the Excel spreadsheet quickly goes to 4kb with about 1500 rows exported. Then it stops and nothing happens for 45 min to 3 hours. Then, all of a sudden, boom, and the entire resultset is exported.

Any suggestions?!?