I have a Win7 32-bit desktop where IE11 started stalling until I clicked a few other items. When I started the Task Manager to see what was going on, everything worked normally. Firefox and Chrome do not exhibit this behaviour -- It's strictly an IE issue. In my searches, I came across a 2-year old issue with a trojan that created a service called "SearchIndexer" and executed "igfxupdate.exe", but it manifested itself by cranking CPU usage to 100%. The commonality is that it disables itself when Task Manager is started, so it won't be evident. This seems to be similar.
As long as Task manager is running, IE behaves normally. I've tried scanning with Windows Defender/Security Essentials and a fresh installation of AVG 2014, but they both come up empty.
There are two IDs on that computer, so I tried logging off one and logging on the other to see if the problem was specific to one user, but the same thing happens. I'm considering removing IE11 and going back to IE10, but I suspect that whatever this is will attack any version of IE.
Has anyone seen this, and does anyone know how to fix it?