1) What happened
Performance issue when using PolygonCollider2d.SetPath(). This example shows the timing difference when using MeshCollider's sharedMesh vs Polygon2D's SetPath. It takes about .3 seconds to get the component of an object and copy the mesh over, but it takes about 1.9 seconds to get the component of an object and set the path. These numbers are for 1300 vertex objects and the Console window will show times for smaller amounts of verticies.

The performance difference seems to lie somewhere in PolygonCollider2D.SetPath as the functions are not calling anything else differently. To see this open the SpawnTest.cs file and the PhysicsWrapper.cs file. The SpawnTest's RunBlobSpawnTest() function between the first stopwatch, calls PhysicsWrapper's CreatePoly function. If you look at PhysicsWrapper.CreatePoly you will notice the difference. This performance issue may not be able to be fixed, but it is worth pointing out.

2) How can we reproduce it using the example you attached
To reproduce the issue, which I already have done, open the project and open the SpawnTests Scene press play and until the console window logs "Done." This will take about 5-10 minutes and will seem like iit is hanging, but is trying to execute the Code. Once the program has finished running view the console window for timing information.

Note that I have not had it crash and the function works properly, it just takes a long amount of time with high amounts of verticies.