In the canvas run, the same rows and cells stay in the page at opacity 0 over the canvas (ResultsTable.tsx on perf/53-canvas-grid), so each dragged frame may still be paying for style and layout on the ~1,500 new cells, with only their paint saved. Did you try a run with that layer cut down to the focused cell, to see whether the 66.7 ms dragged frames move at all?