Your "the rhythm is too complicated for me to play slowly and precisely" reminds me of an amusing story.
Once, when I was six years old, I turned on the hot water in the bathroom. It wouldn't get hot (I waited and waited, of course) so I left it running, went downstairs, and asked my father to fix it. He said "Let it run a little longer." Well, I had tried that, and I told him so. And he said "Let it run a little longer." I tried to explain to him a few more times, and he just kept repeating himself and grinning at me. Finally I got annoyed, stomped back off to the bathroom, and of course found that the water was hot. Which annoyed me even more, of course. The life of a six-year-old prima donna isn't an easy one.
So, my first tip is to keep at it. You have to be patient, and you have to persevere. At some point the rhythm won't be too complicated for you to play quickly and precisely.
Next tip. Sometimes, you have to start by stepping back and analyzing where the notes hit in relation to one another. Here's a difficult rhythmical problem that I had in college, from Debussy's L'Isle Joyeuse:
How to tackle that? Not so difficult to play the hands apart, but when you put them together you have five against three, five against two, and even some five against six where the 16th notes are.
I started with the five against three (bars 3 and 4). Five times three is 15, so I subdivided the measure into 15. The top notes hit on 1, 6 and 11. The bottom notes hit on 1, 4, 7, 10 and 13. So, I practiced it first by tapping my hands on the table.
I started by tapping 15 times per bar in the left hand, accenting where the notes fell, while tapping the right hand only where the right hand notes fell. Then I went the other way, tapping 15 times per bar in the right hand, accenting where the notes fell, and only hitting the left hand where the left hand notes fell. Eventually, I began to get a feel for how everything fit together and started tapping each hand only where the notes fell, going DAH-dah-dah-DAH-dah-DEE-DAH-dah-dah-DAH-DEE-dah-DAH-dah-dah in my head. Then I went back to the piano and started working on the actual notes.
Eventually I could just play it, without that 15-beat subdivision running through my head. Then I did similar work on the other polyrhythms, and eventually had the whole passage down. (Too bad I didn't put as much work into the rest of the piece.)
The same will happen for you, but you have to analyze how everything fits together.
One more tip. Go to the link, click on the first bar of the difficult area and play it back at 50% (see the metronome icon on the toolbar). Listen to it over and over again until it gets baked into your head. Then see if you can play what you hear.
That way, you're putting another part of your brain to work on the problem, sort of a left-brain-right-brain approach. If you work at it from both directions, you should make quicker progress.
But the most essential thing is to keep at it.