hi @Bryan, thanks for the pointer. Before experimenting on Bokeh I was trying with PySide2 + Pyqtgraph, and had experiment with downsampling technique to reduce the number of data point to be drawn on the screen when I zoom out. When I zoom in, it will recalculate the density and automatically fill in the detail so that the number of data point remain the same. Another experiment I did was convert the lines into QtCharts.QPath object. Both outcomes were pretty good, but the latter is much better. I believe Bokeh can do similar optimization there.