As a test I decided to create a simple \"Hello world\" app in Delphi using Delphi 4, 5, 6, 7, 2005, 2010 and XE3. The app is nothing more than a TForm, a TButton with an On
I figured out the problem. Chalk this up to the fact that I use Delphi 7 99% of the time when I develop, and XE3 is new to me. Even though I had chosen "Release" under the project options and made my tweaks there, it turns out that simply choosing "Release" there does not put the project into Release mode.

Who would have thought that I also had to use the Project Manager panel and double click on the "Release" item in order to put the project into Release mode?

If anyone is curious, the final EXE is now 2,229 KB, which is only 5 times the size of the EXEs prior to Delphi 2010.