When you use Workspace ES 18.104.22.168 in Internet Explorer 6 or 7 and you log in, open an XFA form, and log out repeatedly, the memory usage increases. Usage increases between 500 KB to 3 MB when you close forms, and up to 30 MB when you log out of Workspace.
This is a bug in Workspace 22.214.171.124. Contact Enterprise Support to obtain a patch for LiveCycle ES 126.96.36.199. Or, use LiveCycle ES 188.8.131.52 or later.