When writing a novel, words appear in my mind a little slowly, and there are not many words that can be thought of at one time. Sometimes it takes me a long time to think of a paragraph.
You can draw a sketch of the story in the form of a stick figure first, so that you can understand it, and then describe the story in words according to your own sketch, which will improve the speed quickly because you have a clear goal in mind! Then practice more.