No immediate response after entering password at Unity greeter

Under 13.04, unlike in 12.10, there is nothing to indicate that Unity has heard me enter my password and press enter.

When I enter my password and press enter at the graphical login for default Ubuntu, there is no immediate response. It can take 10s of seconds (?) sometimes before the screen changes (ie, until login/startu pis nearly complete). Intead, the password box should go grey or some splash should appear to acknowledge what's happened and make the user think the login is progressing.

ProblemType: Bug
DistroRelease: Ubuntu 13.04
Package: unity-greeter 13.04.2-0ubuntu1
ProcVersionSignature: Ubuntu 3.8.0-14.24-generic 3.8.4
Uname: Linux 3.8.0-14-generic x86_64
ApportVersion: 2.9.2-0ubuntu4
Architecture: amd64
Date: Mon Mar 25 20:23:49 2013
InstallationDate: Installed on 2013-03-18 (7 days ago)
InstallationMedia: Ubuntu 13.04 "Raring Ringtail" - Alpha amd64 (20130318)
MarkForUpload: True
SourcePackage: unity-greeter
UpgradeStatus: No upgrade log present (probably fresh install)