Saw on a computer news site that a company called Cybereason is offering home users a free program to protect from ransomware, even though the program is geared towards businesses, nonprofits and military. I've had it installed for two days and did not notice any slowdown, so give it a try as an extra layer of protection (only works with Windows 7 and higher):
https://ransomfree.cybereason.com/
https://ransomfree.cybereason.com/