I think the problem is that EmulateIE10 is slightly broken: it sends "MSIE 10" but also "Trident/7.0". Real IE10 has Trident 6.0. This looks like it's screwing up the UA regexes.
Google is detecting the user agent string and attempting to use features that should be supported. e.g. google's code is trying to use some IE11 feature that IE10 didn't support. The compat settings are making this fail which seems to cause google's code to drop to it's lowest compatibility mode (IE 6?) as some sort of 'compatibility panic'.
There's another section that overrides the backwards/forwards cache setting for google.com:
But I've no clue how that would affect rendering so much.I've disabled both settings (commented out) and will report back if commenting them out fixes Google.