I remember a few months ago looking at a story about humans arriving on a planet and finding a microscopic alien race. This microscopic alien race lived on a different time scale where they aged a lot faster than the humans. A short time passes for the humans and by then, the aliens are technologically advanced enough to make contact but then decide not to give any information about technologies the humans haven't discovered yet. Hopefully anybody has an idea as to who the author is and what the title is?
Possibly Dragon's Egg by Robert Forward.
In the story, Dragon's Egg is a neutron star with a surface gravity 67 billion times that of Earth, and inhabited by cheela, intelligent creatures the size of a sesame seed who live, think and develop a million times faster than humans. Most of the novel, from May to June 2050, chronicles the cheela civilization beginning with its discovery of agriculture to advanced technology and its first face-to-face contact with humans, who are observing the hyper-rapid evolution of the cheela civilization from orbit around Dragon's Egg.
Note: @user14111 mentioned this novel simultaneously in a comment...