If OP is a STEM major and writing is not her thing, then maybe 4 pages seems like a lot. Use your syllabus to plot out your time so you won’t be caught writing the night before paper is due. Ask for help. Try writing center or ask professor is he will meet with you and go over an outline or draft.
If you are English, History, Philosophy, etc major, then get use to it. That is about the length of many informal response papers my Ds have written.