Hardware used: AMD Athlon FX-4170 4.2Ghz Quad Core Black Edition, Corsair Vengeance 16GB PC3-12800 1600MHz with windows 7 64bit.
Generating 4096 grid heightmap with 20480 x 20480 attributes / texture map (satellite) took 34 minutes.
Generating 4096 grid heightmap with 40960 x 40960 attributes / texture map (satellite) took 2 hours and used 7.5gb of RAM.
Saving 8192 resolution 5×5 mosaics from 40960 texture is very sluggish, RAM usage peaked at 8gb at that point.