I switched to Firefox because Chrome was keeping my fan always busy (high CPU usage and temperature) and using too much RAM. It was always around 5GB for my common usage. In Firefox it's always around 2.7GB. There were some privacy concerns too.

Having said that, Firefox also has its issues. It is so unresponsive sometimes, giving long hangs. That's the main problem to me. There are others, like it being slower in some pages and some of its extensions UI give me a pre-web 2.0 vibe or look abandoned. (But its Mendeley importer extension is way better than Chrome's).