Could you please share some information with us?
The Whiteboard version. The latest version is version 2.12.5.
The IFP 70 firmware version. You can find it from "Setting" -> "Above device" -> "Build number"
Under some circumstance the writing acceleration is disabled and it might be a little bit laggy:
Writing on the AI Pen panel.
Writing with embedded browser is on.
Writing with YouTube widget is on.
Does the laggy writing happen with any of the above scenario?
Finally it would help us a lot if you can kindly send us a short video to demo the laggy writing.
Thanks a lot!