Removing unused edges

I subdivided a cylinder 7 or 8 times to make a spiral horn and there are so many unused edge points it looks like a solid color!
this as you can guess slows down my box like crazy and as there unnecessary i was wondering is there is a shortcut or a button to merge edges that would not take from the final quality

or maybe for future reference if anyone can tell me how to subdivide without subdividing all sides

thanks for your help!

There is no magic button.
You should have used a Subdivision Surface modifier. You can set a different level of subdivison for the 3d view and for your render. You can have a high subdivision for your render but a low level in the 3dview so it doesn’t slow the view down.