OS X Mavericks :: Spam Malware In Chrome Browsing On IMac 10.9.4

I'm having trouble with Browsers.  I rotate between Safari, Aurora, and Chrome. But all three of them eventually choke of resources and hog the cpu.  Sometimes quitting the broswer works but most of the time, I reboot of OS X is needed to clean up the resource logjam.My practice of using a lot of windows and tabs is at least part of it.  But if varys on different days.  Thist week began a new bothersome and worrisome behavior that has malware fingerprints.  Sometimes when I click on a link on a window that is "normal" size (say 60% height and 60% width of screen), a full screen pops up over everything and something I didn't ask for shows up.  There are several cases of what shows up. 

1.  Some times it is a window that advises me to clean up my Mac offering a tool to do that (I've seen this offer all the time but I cannot recall which one it is but it is very common--I think the thing that was offered was Mac Keeper about which I have heard bad things so I avoid it.  It appears to have a foot hold on my system).  clock the red close button on the window (or Cmd-W) and it disappears and the window it came from reappears and is functional.  I can no click the same link I had used before and now it works.  Sometimes,but not always, later windows as I navigate do the same thing. 

2.  Today, when I went to URL.../support and clicked on discussions, a full scren window popped up with the URL.....or some other thing - I've only captured the two URLs. If I close that popped up window

Info:
iMac, OS X Mavericks (10.9.4), 27-inch Mid 2011 2.7 Ghz Intel Core