System Information
Operating system: Windows-10-10.0.18362-SP0 64 Bits
Graphics card: GeForce GTX 1080/PCIe/SSE2 NVIDIA Corporation 4.5.0 NVIDIA 445.87

Blender Version
Broken: version: 2.82 (sub 7), branch: master, commit date: 2020-03-12 05:06, hash: rB375c7dc4caf4
Worked: (optional)

Short description of error
When I use smart UV project on my mesh it hangs and then never finishes.

Exact steps for others to reproduce the error
I created a mesh from a pointcloud in MeshLab. Then imported it as an OBJ to get uvmapped. I decimated to about 1 million polys. I ran a sample mesh through smart UV project at 0.3 island margin and it worked in about 35 minutes. But another similar mesh (the real one) also around a 1 million poly count just hung for 12 hours and nothing ever happened. Is there more information on the smart UV project tool that handles meshes differently? I understand it isn't a one solve all button and it's hard for you guys to troubleshoot without a sample mesh (it's really large). But some insight on this might help me make better decisions on what I can do differently. Thank you!