VegaProf: Profiling Vega Visualizations

loadData() -340ms initScales() -60ms renderMark() -10ms 1 -Icicle Graph 3 -Dataflow Graph 2 -DSL Specification Figure 1: VegaProf records low-level execution times and encodes them in coordinated visualizations corresponding to different abstraction levels of Vega's DSL execution. (1) An icicle graph provides an overview of where most time is spent. (2) Unlike previous debugging approaches, which relied on trial-and-error-based changes of the visualization specification, VegaProf maps performance measures directly to the Vega specification. (3) To help analyze performance on different levels, VegaProf augments the dataflow graph with performance measures.