Slow slicing in Cura

[Pyrotactics 0]

Hi, I am new to 3D printing.  Originally, I was using the Creality Slicer software that came with the Ender 3 Pro that I got, but for some reason it wasn't generating a gcode when I would try to slice something.  As a result, I recently downloaded Cura.  I have sliced several models and printed them no problem (though I did notice the slicing was a lot slower than the other software - previously slicing took a few seconds, now on Cura its taking a few minutes).  This morning I tried to slice a model with the exact same setting as the last thing I printed, and now the slicer isn't moving past `30%.  Layer height is 0.2mm and all the other setting looked fine.  How can I fix this? Or how can I speed up the slicing process?  Ideally I'd like to be back at the few seconds to slice.

[ahoeben 1,968]

Some settings make the slicing take longer, eg setting the support type to "Tree" instead of "Normal".