Is this new? I tried it out a couple years back on a decent spec phone and it was the slowest app I've ever used. I'm pretty sure Snapchat the app was known for being sort of a wreck at some point. My daughter still put up with it but it was painful to watch her use it.
I have a fairly high end Android phone (OnePlus 3) and Snapchat freezes up all the time. Video pretty much always stutters without fail. IIRC it was the same on my Nexus 5 as well.