Hi all,
As guinness stated, the size of an uncompressed AutoIt program is nothing compared to the size of hard disk drives we're using these days.
Also, a compressed program doesn't use less memory when executed. The only gain you have, is used space on the drive.
Of course, when distributing programs the size does mather. But I would suggest using an installer like NSIS which compresses your (uncompressed) AutoIt program and adds only about 35 kBytes of overhead.
Edit: typo