A great example from, it all depends on when exactly you want to change the speed of the animation, I think that events, in the example from Suzzy-Grey, can be edited for any task.
I tried using a gif from Giphy.
I had the same problem as you where the gif runs full speed and ignores the slider.
I suggest you use gifs from google image search or make your own at https://www.piskelapp.com/
It’s probably better to avoid using gifs from Giphy unless you just want a gif that auto animates and looks pretty.