The number of pools and rivers and placement and so on is all pre-decided so they are going to be placed; if it looks too busy then that is my fault for over-complicating the map.

However, what you have to realise is that this is a very zoomed in view of a HUGE map. At 40 x 40 squares it represents 200 feet x 200 feet. If printed out, this map (4000 px x 4000 pix at 72 ppi) would take up 55.5 Inches each side - that's four and a half feet (1.5m) tall and wide. It's the biggest map I've ever attempted and my (relatively decent) computer can barely handle it.