The following layout test is timing out on GTK Release builds, while passing just fine on Debug ones:
The test has been timing out since it was added on r189264
Here's a test that creates a multiEntry index on 250000+ items. It fails in WebKit, so I guess it's the same issue?
Chrome also fails, so the fix may be similar. https://bugs.chromium.org/p/chromium/issues/detail?id=681980