What is most efficient way to setup http profile with ram cache

Are you trying to do this check based on the request URI? I see HTTP::uri in your switch, but some of the values in the switch cases don't look like valid URI patterns.

First, HTTP::uri always starts with a "/". Secondly, you have other folders in your example path (/app_themes/default/images/icon.check.png) before the "image" folder in your switch case. So I think you need to change some of them as follows...

 
when HTTP_REQUEST { 
  set debug 1
  switch -glob [string tolower [HTTP::uri]] { 
  "text/*javascript" -     this looks like a content type.  Do you really have a URI pattern in the site that looks like this?
    "*/scripts/*.js" -     needs to have a leading wildcard
    "text/*.css" -         is this a content type, too?  Or should it have a leading wildcard?
    "*/images/*.swf" -     needs to have a leading wildcard -- and the "s" in "images"
    "*/images/*.gif" - 
    "*/images/*.png" - 
    "*/images/*.jpg" - 
    "*/images/*.jpeg" 
    ...