The trick is to update the smallest area of the screen. e.g. overwrite a Sensor value or animate a bar graph.
Animating a meter needle is fairly complex. You rub out the old needle by drawing in the background colour and then plot the new needle in the foreground colour.
But most importantly. You only draw something if it has changed. Whether it is a needle, graph point, numeric value, bar, ..., colour, ...
I have not looked at the DFRobot library. The speed should not be noticeable if you follow the above strategy. Bear in mind that humans can only read numbers or text at a moderate pace. No point in updating more often than necessary.
If you have any "other" colour displays, port your code. Compare performance.
David.