I've found that google maps performs worse in firefox and I get random %100 cpu spikes from websites in firefox that I didn't get in chrome. I'm on a mac using firefox 55.
Firefox 55 doesn't have any of the (massive) improvements from 57 and Project Quantum which are being discussed here. Give Beta, Developer Edition, or Nightly a spin.
I've found out that many google products (web pages) have bad performance outside of Chrome[0]. But I've used Netscape/Mozilla my whole life, and I will not change from it, specially now that its performance is measurably rising (again).
[0] which is of course something google devs should consider and fix the sites, but hey... why do that when you're the market leader?