After installing 10.5 I noticed some documents were taking much longer to open, some 4 to 15 minutes and others would not open at all.
Initially I thought some databases/rasters were corrupted but it took some troubleshooting and a machine that still runs 10.4 to realize that the problem is in 10.5 specifically any document that contains a raster function layer even if it is turned off takes exponentially longer to open / refresh. (the more raster function layers in the document, the worse the problem)
Removing all the raster function layers solves the issue and the documents suddenly become as snappy as before. Naturally, the next step was to attempt to rebuild these raster functions from scratch in 10.5. Using the Image Analysis window and simply selecting a hillshade and an imagery raster and hitting the pansharpen buton to create a raster function layer takes MUCH longer in 10.5. It does work and eventually a raster function layer is loaded in the TOC, however, is take a very long time and further attempts to tweak the function / raster function chain is not possible because the Function tab in the Layer Properties crashes.
Has anyone encounter similar issues and if so, is there a workaround? Because most of my 100s of documents contain raster functions, I may have to downgrade to 10.4.1 but I am hoping for a more elegant solution. I already created and resaved a number of documents which makes these incompatible with legacy ArcMap versions so I will need to resave all these as 10.4 copies first.
Update: After a back andf forth with ESR, this was confirmed and is now a BUG-000103911. The workaround is: Downgrade to 10.4.1