Q: Macbook Pro running extremely slow

While still on Mavericks my Macbook Pro 13 mid 2010 (2.4 Intel core 2 duo) sporadically began running extremely slow functions, even the mouse cursor moved in jolts and steps, to type a word in google search engine I had to wait a few seconds after being typed for the word to appear on screen. The internal speaker volume responds 10 seconds after tapping the buttons on the keyboard.  Videos are unplayable in netflix and other sites because picture freezes and runs in jolts and steps. Its Not the internet connection or the streaming.

I upgraded to Yosemite to see if this would fix the problem, I upgraded the darned adobe flashplayer believing maybe I needed the latest software available for my programs for the computer to run smoothly. I upgraded the RAM to 8GB from 4GB and did not fix the problem. I have more than half of the 500GB hard drive with free space. I'm getting a Java Runtime Environment download prompt to view properly something every time I boot the computer.  The "slowness" comes and goes. But it gets more frequent and worse each day. I can't work.  Could it be some type of malware that makes the computer slow? I can't identify a specific malware to address and remove. Could it be that the fan isn't working properly and runs slow when its too hot?? Please HeLP!!