Meet Cenotaph! My testing subject for comparision presented below.
Besides visual quality this picture presents quite good data sample for compression tests. After processing it with bmp2cgb I ended up with usual attribute, tile and map files. Each has its own characteristics. Attributes contain repeating strings, tiles have a bit of everything and map is the toughest nut, containing mostly unique bytes. Each file has been packed and then unpacked in emulated environment to count exact amount of cycles used. In case of raw data it was calculated from standard unrolled copy routine. The results are as follows:
