Last Update: 1/3/2019
Sometimes the speed mode setting remains on although you have turned it off. The reason is that some of the contour lines cannot be drawn because the logical resolution of the screen (which in Origin corresponds to the physical resolution of the default printer), has been met.
This is most often seen when the column:row ratio of the matrix is high, such as a matrix of size 3000x100. In such a case, where many contours approach one device unit in size, and Origin cannot display them, data skipping (speed mode) is enabled.
For all practical purposes, the internal speed mode limitation to skip the data in the larger dimension will not alter the contour plot, so you can decide to turn off the speed mode display on your graph by selecting Preference: Options, Graph tab and unchecking the Speed mode show watermark checkbox.