Starting Session takes really slow - notebook session Microsoft Fabric

We have this as well.  Default envirnoment is very quick, but custom environments are very slow.  It's quicker to %pip install all your stuff in the notebook rather than have it available to import from the envirnoment, which seems pretty mad to me.

Example:

Notebook with %pip install geopandas shapely pyproj fiona contextily, 11 seconds to start session and 28 seconds to run this first big import cell (installing and then importing all my libraries).

Notebook with in envirnoment with geopandas, shapely, pyproj, fiona and contextily installed there, and then import cell having the %pip part removed: 2 minutes to start session and then a further 20 seconds ish to run the cell.