I have the trial of LiveCycle Designer ES2 (v184.108.40.206.2009....) installed. I created a seemingly simple PDF form, but the file size is over 1MB. Is that "normal"? It seems like it would/should only be a few hundred kb, if that.
Your form might have the following line of code multiple times which will cause your form to grow in size.
<?templateDesigner StyleID aped3?>
To fix this, goto XML Source tab of your form. (View menu -> XML Source).
Search for the above line of code and delete.
Then save changes.
That bug was fixed in an earlier version, so should not be a problem in ES2.
One thing to bear in mind is that by default LC Designer embeds fonts into a form (see File > Form Properties > Save Options). This does not add too much to a form if you are using an efficient font like Myriad Pro. However if you use other fonts, like Times New Roman, then this can add several hundred kb.
Also if you are using images in the form, then untick embed images in the Object > Field palette. The image will still be available when the user opens the form in Acrobat/Reader, but will be more efficient.
Hope that helps,