In QuickMap, there is a point reduce check box when you select file->export. This option allows you to specify what is called a "tunnel" which QuickMap uses to estimate how many points to throw away.
If a line with lots of points on it can fit inside a tunnel (shown in red below) then the intermediate points are thrown away. e.g. In the example below, the red line is the tunnel, the black line is the original and the yellow like is what you end up with if you apply the point reduce.
