SQL Editor locks up for a few seconds after executing a query from a large file (4335316)

Steps to reproduce this

Behaviour 1:

1.Open a big file in the editor (about 20000 rows)
2.add a select that you can run on your environment (select * from dual for example)
3.select this select and run F9
4.go to the grid and copy one of the results
5.try to paste it into the editor .SQL Navigator will lock and you need to wait for a few seconds till it responds

Behaviour 2:

1.Open a  big file in the editor (about 20000 rows)
2.add a select that you can run on your environment (select * from emp for example)
3.select this select and run f9
4.once you have the result in the grid press return
5.then press down arrow key and the up arrow key. SQL Navigator will lock and you need to wait for ma few seconds till it responds

With version 6.7 works fine.