Alternative browser for iMac OS X Yosemite 10.10.4?

Safari keeps freezing and after 3 sessions w/AppleCare, the problem has not been resolved. Any suggestions of a better browser to use w/ my iMac OS X Yosemite 10.10.4 ( late 1012 edition) ? Any attempted fixes have only lasted about 24-30 hrs.and then it starts freezing again.