Here's a more technical description from HB_AlexSz of how the optimization update works for TGC 2019:
Rendering hasn't changed with this update - it could be the clouds getting in the way of the sun, maybe? If you have a screenshot it might be easier to diagnose what's going on.
The game's size on disk is so much smaller because the game's data files are now compressed using LZ4 (a compression algorithm which is extremely quick to decompress).
Previously most of the data only had a limited amount of compression - for example individual images were (and still are) DXT compressed. The game has a few data files which each contain a large amount of individual art assets. We didn't have any compression on entire data files before because the game would have had to decompress the entire (large) data file into system memory before using it, which would use too much memory - and most compression algorithms end up taking longer to decompress than just loading an uncompressed file directly into memory from the filesystem.
The LZ4 compression method we're using now is able to decompress small sections of a larger data file, so it doesn't have to load a whole data file into memory if just a few images out of a few hundred in the file are needed. Because the game is a lot smaller on the filesystem and because LZ4 is very quick at decompression, courses now load faster as well.
http://www.hb-studios.com/forum/inde...html#msg315322