XML syntax for tags

Question

It has always been a habit of mine to use XML syntax for CF tags since I've been working with XHTML. For instance, I will do <cfset var myVar = "" /> However, I noticed when doing <cfdump var"#myvar#" />, the output is displayed twice. So now I am wondering if whenever I use a /> on something such as cfset, is the tag actually executing twice? How does this affect performance?
I just happened to notice that in CFBuilder, when I do <cfargment name="myVar" required="true" type="string" default="" />, when I go to the next line and start typing <cfarg auto-suggest will select the cfargument tag, but this is only if I use a />. If I omit the ending forward-slash, auto-suggest does not work. That may be a setting specific to CFBuilder, but that wasn't the scope of this question.
What syntax is correct and how does it affect performance?

Answer 1

According to the document I've linked to below; using self-closing CF tags, such as <cfset myname="Bob" /> is permissible.  The document also notes exceptions to this such as CFIF and custom tags as examples where a self-closing tag shouldn't be used.
http://livedocs.adobe.com/wtg/public/coding_standards/style.html
Althoguh it doesn't look like it, that's an internal coding standard for one of Adobe's (well: it was Macromedia at the time) internal teams, and is not supposed to be a suggested standard for everyone.  I've had this same discussion with them, too.
As Owainnorth (and many others) observe, it's completely doable.  My only challenge to it (and it's a challenge I state in an unduly heavy-handed fashion sometimes!) is the nonsensical rationales people use for doing it: making it more like XML, it's good if the CFML blends in better with the XHTML mark-up it's generating, it's tidier, etc.
I hasten to add that Owainnorth's position that he finds it easier to read and assists with code navigation, whilst leaving me with a blank look on my face, is a completely reasonable basis for doing it.  I personally don't believe it, but there's no reason why that should bother him (and I'm sure it doesn't).
I think it was reasonable of me to challenge his wording that it's easier to identify where CF code blocks are by looking at the closing slash rather than the tag name; but having explained himself better, I reckon it's not quite so much tosh as it originally sounded.  I mean: I still can't see it, but obviously he can, so fair enough.
Adam