I got the exact same issue. Some input delay after pen-down, then nothing for a brief moment of moving, then a straight line to continue to freeform drawing.
This also applied to other tap-and-drag-style operations such as grabbing and moving a layer.
Today I finally decided to investigate and found this thread via Google.
I checked Edit > Input devices and found "Core pointer" and also "WACOM Tablet Eraser" and "WACOM Tablet Pressure Stylus", but the latter two were greyed out.
I turned Edit > Preferences > Input devices > Pointer input API from WinTab to Windows Ink and restarted Gimp.
I checked Edit > Input devices and found all items present, not greyed out, and the input delay gone, performing as desired.
For testing, I switched the Pointer API back but did not see a difference, so I left it.
Now I need to test whether this survives more steps such as reconnection of tablet and/or rebooting of computer, though I want to save this post first.
Gimp 2.10
One by Wacom
Windows 10
This also applied to other tap-and-drag-style operations such as grabbing and moving a layer.
Today I finally decided to investigate and found this thread via Google.
I checked Edit > Input devices and found "Core pointer" and also "WACOM Tablet Eraser" and "WACOM Tablet Pressure Stylus", but the latter two were greyed out.
I turned Edit > Preferences > Input devices > Pointer input API from WinTab to Windows Ink and restarted Gimp.
I checked Edit > Input devices and found all items present, not greyed out, and the input delay gone, performing as desired.
For testing, I switched the Pointer API back but did not see a difference, so I left it.
Now I need to test whether this survives more steps such as reconnection of tablet and/or rebooting of computer, though I want to save this post first.
Gimp 2.10
One by Wacom
Windows 10