Hello, I successfully updated my mid-2010 Macbook from Snow Leopard to El Capitan (at least so I thought). in addition to that I also inserted a new 850 evo Samsung (500GB) + 8 GB RAM. At first, the computer was fast..applications loaded fast etc. But after about two weeks, I am having issues with it....one of it is the noticable drop in speed...to a point where the whole system (cursor) seems to be stalling..also I do see a lot of spining wheels. I can still work on this but it's weird...loading of a stupid built-in Dictionary can take up to 2-3 seconds, before that it was instant. On the boot-up too,before it was fast, not takes much much longer. It almost feels as if I was still running the old 5400RPM HDD. In fact, it can get to the point...just like now, when the letters that I am typing need a split second longer to appear...again, stalling would be the best description...or a feeling as if you were rewinding a movie in slow motion. In Activity Monitor, the CPU usage jumps from 10% to 350%..with something like kernel_task. see printscreen below. It's actually really unpleasant now to work with. On top of everything, the uppper left-hand corner is exteremely hot...and when you place your fingers next to the microphne, the whole aluminium is on "fire"..really hot too touch. The same is true on the back of the computer - the same area. Though my fan is not spinning. And my battery says, when I click on it: service battery (see prinscreent). ps. it does seem that my computer gets hotter with usage..i.e. if I use Word, it stays cool. The trouble starts with browsing the web....certain websites seem to overheat the whole thing..and then I cannot do much. What could be the cause for this? What is happening to my Macbook? I have not experienced anything like this with my previous Snow Leopard. The computer with an SSD and 8GB RAM works much worse than that with 5400HDD and 4gb RMB (and it didn't do this when I freshly installed it). Please help, this is freaking me out!