I have Yosemite. I have recently replaced the battery, new 1Gb hard drive, new 8Mb RAM. Download speed in excess of 80Mbps, Upload around 14Mbps. Constant spinning rainbow. Delays in apps like facebook, twitter, youtube can reach 1 min per command. I have tried anti malware. I am at a loss. My wife's $350 PC has no speed issues with the same applications. What to do?