This is not an issue from SU2017, but some versions above including current release.
When I’ve tried to open a very heavy SU file (200+Mb) it always opened too slow. This weekend I decided to spend some time testing several options with a 330 MB purged file:
0.- I use SU 2017 Pro (on i7-5820k, 16GB, GTX970), with V-Ray 3.4 and about 20 more plugins (from Fredo6, Thomthom,…). Time to open: more than 25 minutes.
1.- Deleting / deactivating some plugins I observed fast results only in startup SU (no skp file involved) When open file once SU is running 've found no significative results (maybe little better without 1001bit tools, but not much to have a great performance time, not relevant) (I didn’t test without V-Ray even when I know open file performance is much better without it, but I do need V-Ray)
2.- I decided not to show the tray (windows release) and the same result: more than 25 minutes. (my configuration for tray shows Entity info, Layers, Shadows, Materials, Components, Styles, Scenes, Outliner)
3.- I tried to quit some windows from tray and found a combination that drastically works for me: Quit Materials and Outliner from tray (Layers, Shadows, Info, Components and Scenes don’t seem to affect open file performance). Time = 32 seconds. Once file is open I can open these windows in tray again and everything works great
I post this here for any to explain or comment.