A big part of adjusting to university is learning to read properly. Reading for a degree is different to reading for leisure. I don't know how it is for economics, of course, but for my course I have to do two 2000 word essays a week, plus the work for the language component of the course, plus lectures and supervisions. For each essay there's perhaps 3 or 4 books, on average 400-500 pages each. So that would be 2000 pages a week on the essay reading alone.
You're not meant to sit and read the reading from start to finish as you might read a novel. Start by reading the introduction and conclusion to get a feel for what the author is saying and what they've found out - a nice short summary. Make use of the contents page and the index to find the relevant areas, read the introduction and conclusions of chapters before skimming the text to establish whether any of it is relevant. You can even read the first line of a paragraph and the last line of the paragraph to establish whether the paragraph seems relevant and worth reading in its entirety.
We were given a compulsory study skills session during freshers week - not your typical alcohol-fuelled freshers romp, but it outlined all of this stuff very well.