Query executed only first time in a session

hi there i have a simple query returning 200000 records and is executed successfully when i executed in new query window first time in less than 20 secs but when i again hit f5 it takes too much time and cannot be executed.

When i again execute this query using another session ie new query window it again work fine.

Please suggest me to resolve the issue, there is no index is created on table and table having 5000000 records in total and query returns 200000.

thanks in advance.

Instead of getting results in Query result try to save Query result in file. because the counts are huge may be issue because of the count of records.