Hitting a plateau with Khmer complex vowel symbols

I’m an intermediate learner and I feel like I’ve hit a wall. I can handle basic sentences, but the complex Khmer vowel symbols—especially when they combine with subscripts—are slowing my reading speed down to a crawl. It’s hard to keep up with news articles when I have to decode every single syllable stroke by stroke. Is there a specific way to group these symbols for faster recognition, or is this just a stage I have to grind through?