Yes, the screen refresh that it does when inserting or deleting lines can get annoying and takes some getting used to. One time saving tip if you want to insert several lines is to go past the end of the program and drag a few more blank lines then you think you'll need and then right click "copy". Then go back to where you want to insert code and paste the blank lines there. This is sure faster then inserting them one by one. You can also delete several lines that way, by dragging over the ones you want to get rid of and then right click "cut". Then you just don't paste them anywhere...
Btw no, you cannot use the old 1.70 editor any more. The editor is also the compliler so they cannot be used seperately.