The function crossing_number runs too slowly?

In graph theory, the crossing number *cr(G)* of a graph *G* is the lowest number of edge crossings of a plane drawing of the graph *G*. In general, determining the crossing number of a graph is hard. However, for graphs with a small number of vertices and a small number of edges, some efficient procedures exist to compute them. The *exact* and **non-heuristic** programs that I know of are the following: - sagemath - web crossing number (http://crossings.uos.de/) #Recent login is not available, the website may be under maintenance, or maybe not to provide services in the future. - [OGDF](https://ogdf.uos.de/) (that is a self-contained C++ library for graph algorithms, in particular for (but not restricted to) automatic graph drawing.) I see an example of mathoverflow from 10 years ago, which is to compute the cross number of the Grötzsch graph. - [cross number of the Grötzsch graph](https://mathoverflow.net/questions/94282/crossing-number-of-the-gr%c3%b6tzsch-graph) Jamie J. Taylor says in the answer that OGDF can be used. But we don't see the corresponding code. I know that Sagemath has the crossing_number, Unfortunately, it may be too slow. G = graphs.GrotzschGraph() G.crossing_number() It took me about 12 hours, and I haven't gotten a result yet. Perhaps there is some way to improve it?