We are looking to improve performance in PS web, and we use querymode for searching.  And, in order to get around all of the limitations of querymode, we use sqlpreview to add missing functionality to the querymode processing.

These tidbits for sqlpreview are listed in the powerserver docs:

1. Each time the DataWindow SQLPreview event is triggered, the mobile/web application will interact with PowerServer twice, which costs 1-2 seconds. Therefore, Appeon recommends you minimize writing script into the SQLPreview event of the DataWindow.
2. ...sqlpreview event will generate one call for each line of code handled by the event.

Which of these are true? The first one says TWICE at 1-2 seconds, the other says 1 per line of code.  These can't both be true.

Does a comment count as a line of code?  

If i only have a comment in sqlpreview, does the event still get triggered?

Does a call to a method on an object count as a single line of code, or does each line of code in the method count?

Are those statements equally true for datastores as they are for datawindows?  

Is that 1-2 seconds still an accurate estimate?