actually CAD may be more compute intensive, if 3D calculations and clipping are involved. Charts are pretty simple 2D shapes, text should be easy. One problem the electronic cartographers face is that the hardware in chart plotters is woefully underpowered and behind the technology curve, probably less compute power there than in my phone. Even the latest doesn't zoom the same chart as fast as on my phone. If only chart plotters could be made a few million a year rather than a few hundred (prototype quantities, for a cell phone manufacturer), the situation would change. Another issue is the the cartographer has to accommodate both brand new very expensive hardware as well as 15 year old extremely primitive hardware. Your Navionics cartridge is expected to work on both.