I never would have made it through graduate school if I actually read everything I was assigned. Can you split up some of the readings with those in your cohort and share the summaries? I also became good at skimming articles for main points...reading the methods and results more closely and skipping through the intro and discussions. It probably takes me well over an hour to read an 8 page article to the point I truly understand it, and there just isn't enough time in the day for all of that. It's necessary for some papers, and not so much for others. Part of grad school is figuring out what is important and what is less so; that's the time management piece.
As for active reading and retention, you have to hone the skill of being able to pull out the central arguments in a paper. After you read a paper, try to write your own abstract for it--make sure you understand approximately what they did, what was being measured, what they found, and why it was important. The more you do this, the easier it should become. Then try to tie it to something you already know or something that interests you. If you truly want to learn the material, you have to process it deeply, not just memorize.