Assuming you've done the advice in the curriculum (really slowing down, making low- res summaries, and such), I would suggest trying to change your mindset going in if possible. I noticed improvement when I fixed my mindset. RC is not my strong suit compared to LR, because I know I am just not typically interested in the longer commitment to whatever topic. If you can hype yourself up into believing that the passage is going to be interesting, you'll retain the information better. The dread of doing RC can hold you back.