nodeSet, nodeList, and $fooo/@bar

I was trying to use xalan:node-set() one day, with errors, and on a whim
just went ahead and did
<xsl:for-each select="$foo//*[(_at_)bar]">

and to my suprise it worked.

Now i may have gone overboard.  This are getting S-L-O-W and i'm not sure
why.

Is there any difference bewteen "x:nodeset($foo)/@bar" and "$foo/@bar"

and what are the costs of using this trick?

any optimization tips?

PS:
i still occasionally get the "Cannot convert #STRING to a NodeList" error.
Not sure why.


 XSL-List info and archive:  http://www.mulberrytech.com/xsl/xsl-list