IDE-1.0 IS BUGGY!

and why the file extension change?

I think you will find a setting under preferences (from memory) that 'changes to .ino'.

This may resolve this situation you have.

Personally I haven't found it slower, but you can still download and use ver 023.
As I understand some code needs changing because they have changed some keywords in (Wiring.h ???).
I found it when trying to load an old sketch that worked in previosu versions, using Ver 1.0 into my Nunchuk controller Robot.

In the end I went back to 022.

Mark