Primer is absolutely nothing like The Zero Theorem. I'm not saying it's not a good movie but it's completely the opposite of TZT in every way. The way it's filmed, it's realism as opposed to TZT's surrealism, the narrative style....basically just everything.
Reaction time is a factor in this, so please pay attention.
Cloud Atlas, Trance, Arizona Dream, The Congress, Jacob's Ladder, Most People Live in China, Songs From The Second Floor, The Project, Donnie Darko
Primer is good stuff, it's just not presented in the cinematic language we are used to in the 21st century. So, if you want to 'get it', (and still didn't get it the first time) well, you'll just have to watch it more times. For me it's kind of the same as with Fellini's 8 1/2. The more I've seen it, the more I've liked it. And I REALLY disliked it the first time.
You should see the French movie Thomas in Love. To put it mildly, more than several things in Zero Theorem are lifted straight out of it (pretty much all the aspects other than the zero theorem stuff itself). I love both movies.