Rowzero is a better spreadsheet, while PySheets is a better Jupyter Notebook. Although they converge in certain aspects, their distinct target audiences set them apart. This divergence may create some overlap, but it also leaves ample room for user preference.

PySheets currently runs inside the browser, on top of WebAsm, and the limitations there are bigger than just Python's slowness. You have only 4G addressable memory, including the interpreter and libraries. Network bandwidth is also a limiting factor for client-side computation.

That said, PySheets can render a sheet based on a 50,000-row Excel sheet in 0.5s and needs about 20s to do a full end-to-end recompute run. There are limits to what you can do in the browser without using an external kernel that can run Polars on large datasets. But, I think most people will be fine with what PySheets can let them do.

Finally, as the author of PySheets I am honored that a "competitor" sees us as a threat. I am quite impressed by Rowzero myself. Nice work :-)