Hidden line rendering time can vary by 30 times (10 seconds vs 300 seconds) between rendering 'WITH' or 'WITHOUT' 'surface hatch' in background. Note the progress bar at bottom right of video clip.  I believe this issue is only replicable on large file using project sharing, and not in isolation.    (NB to vectorworks similar issue already discussed with Jim Wilson via email on 6th March, 2019).     5 seconds without surface hatch_ (1).mp4 5_minutes_with_surface_hatc