I haven't tried using DataGridXL with a file with that many records. There is a chance that the DOM node that is used for scroll-listening grows too large and browsers cannot handle that. I suspect that is where the error comes from.
However, I will add this to our list of issues, see where the error really comes from and where I can improve it (https://github.com/DataGridXL/DataGridXL2/issues/31). For now, I would say 10,000 records max to be sure.
Feel free to steal and improve, we only enable the clown-car mode when the desired scrollable area is larger than what a browser can support. With our implementation scrolling is still handled by the browser, but the scroll location can be subtly recomputed as you go from time to time. We only do this when interacting with the scrollbar directly to avoid weird artifacts like scrolling feeling faster than normal.
However, I will add this to our list of issues, see where the error really comes from and where I can improve it (https://github.com/DataGridXL/DataGridXL2/issues/31). For now, I would say 10,000 records max to be sure.