XSL:KEY VS XSL:VARIABLES

[Jean Croteau]

Hi,   We are working on a project with multiple languages and we want to know if their is a performance issue when using XSL:KEY with an xml file (using a <xsl:for-each> on a document) vs defining a whole bunch of xsl variables and doing a xsl choose.   Does Xalan load the keys into memory ?  How does it manage the xml files that it imports ?  Any information on this subject would be appreciated.