Our team uses Ivy/IvyDE, and noticed Eclipse hanging today/yesterday, to the point of being unusable.
I tracked it down to Eclipse asking IvyDE "is this your file?", which IvyDE's IvySettingsContentDescriber used XMLHelper.parse to answer, but then Xerces hung while trying to load the XML file's DTD.
So, the problem was the DTD being unavailable, but it seems like XMLHelper should turn this off, especially if the schema parameter is null, and it's in non-validating mode.
The attached patch turns off external DTD fetching when XMLHelper is already in non-validating mode.
This avoids the wire call, which speeds up the XMLHelper.parse by at least 100%, ~250-300ms when fetching the DTD, to ~100-150ms when not. (And this is the happy case, in the worst case, waiting for the timeout if the DTD is unavailable, takes ~20s).