I can't open your map right now, but check your sheet order. The behavior you describe is exactly what happens when the symbols go to a sheet that is hidden by something else, for example a landmass.

For performance reasons, when you place symbols, they will always appear on top of everything else, but once you change the view in any way, the view is recalculated, and everything goes into the correct position based on sheet order. The fact that the symbols disappear means that they are on a sheet behind something.

Also note that the Shaded Polygon command changes the fill style to whatever is currently selected. You can use :CC2KEEP: to set the current settings to match that of your poly before running the command. Or you can use the Shaded Polygon (Angle by Edge) command which doesn't do this, and at the same time figures out the correct angle for you.

This is due to the particular fills you have picked. Unfortunately, most templates contain some truly ancient fill options which doesn't work very well with modern CC3+. These are the leaves, tiles, stone and woodgrain fills in the list. Avoid these. I am unsure which style your map was made in, but if you have Dungeon designer 3 (DD3) or Symbol Set 4 (SS4) I recommend starting a map in one of those styles as they contain proper bitmap fills you can use with the room and corridor commands. If not, you should also have access to the Annual John Roberts dungeon style which also have nice fills.

You'll normally also want to avoid those vector (line) based fills.

Yea, fills in CC3+ are always drawn without rotation regardless of the angle of the room. You need to use the shaded polygon command on them to rotate the fill

This is again down to your choice of fill. This command only works with bitmap filled entities. If you use one of the proper bitmap fills from the styles I mentioned above, it should work fine.

For the Dracula dossier, I am guessing those geomorph floors weren't intended to be there. Ralf repurposed an older set of symbol catalogs, as they work fine with that particular style, but I guess he forgot the geomorph catalog. The reason it doesn't work is that the fill style used for the floors in the symbols doesn't exist in the actual Dracula dossier template.

That should work fine. Make sure that you include the System subdirectory of the CC3+ data directory, as this is where all the settings for the symbol catalog settings, master filters and drawing tools are stored.

Note that symbol catalog settings can also usually be fixed manually quite quickly unless you have a lot of them with problems. The most common issue is the file name of the actual catalog being removed from the setting, but the name of the setting itself should be enough to identify which catalog it needs, so you can browse to it and then save the catalog.

The software is 32-bit, so it can't address more than 4GB of memory, which it should do by default.

That said, the rendering is CPU-bound, so unless you are manually forcing it to always use very high quality textures in the display speed dialog (a rather bad idea btw, since it won't affect visual quality, CC3+ automatically uses the right textures based on the current zoom level, manually overriding it just eats performance with no benefit) so the rendering speed is mainly limited by CPU-speed (Actual clock speed is the most important here, not the number of cores) .

Note that since CC3+ is a vector-based program, it will need to re-render your display every time you change view, it is not a finished bitmap just laying ready in memory as with regular image editors. The amount of work needed here depends a lot on your display size, for example a 4K display is 4 times as many pixels as as 1080p one, so it will also be 4 times as slow in that case.