I use a Wacom One table and Photoshop. If I put the pen on the tablet and try to draw a straight line, Photoshop immediately draw the line as I move my hand. However, if I put the pen on the tablet and start to draw in circular motion as to fill the area where the pen touched the tablet, it does not show my coloring until I take the pen off the tablet. How can I fix it? I want as I am filling a small area Photoshop shows the paint as I move the pen.
This sounds like it could be low RAM, or an inadequate graphics card, or both... Photoshop is having trouble literally "keeping up" with what you're painting.
Test if it's low resources by doing the same thing with a far smaller document, with a far smaller brush size - with more frequent saves.
Do you see a change in the behaviour?
If yes, if there's a noticeable improvement, then you have a low resources issue.