Performance issues with jsonld.normalize

[william-vw]

I'm having some issues with jsonld.normalize. It works really well but it currently hangs at a seemingly arbitrary point. Feel free to checkout the code here: https://github.com/william-vw/pyld_normalize_test.

A single additional triple in the test file perf_test2.ttl means the difference between sub-second and > 5 minute performance (at least on my machine), which may indicate an issue with the implementation.