How do I reduce the length of an animation?

I have a short animation that contains 110 frames. I want to reduce that to 55 frames for both duration purposes and file size purposes. I want to keep all of my keyframes, but half the number of frames in between. I understand that everything will happen twice as fast, but that’s what I want.

How can I achieve this?

Regards,

I’m no pro at this but I would assume setting the ‘steps’ bar below ‘start’ and ‘end’ to 2 will make you render 50% of the frames. Alternatively you can just up the frames per second, but it will still render the same amount of frames.