Friendly speaking, we didn't make a performance or optimization research yet. I can only share an experience we've got from using taucharts in our main product - "Targetprocess". So we setup a limit to 1000 rows (+/-50%) which seems to be acceptable performance / usefulness balance to draw a chart within a 0.5 seconds. Also it depends on chart type. Drawing huge facet with more than 100 cells in it can be painful while plain scatter plot on the same data works fine.