Earlier today I had a few apps open, and one of them was Safari, which had some tabs open which may have been using a lot of energy and/or memory.
(One of them was this program by me which draws a grid of squares in isometric 3D, but unfortunately creates and stores a new object literal in the memory every time the function gets called to map a point from 3D onto 2D. This function gets called about 1600 times each frame, about 60 frames per second. Not a big problem unless I left it open for a while, which I did.)
So then I got the spinning wheel of death on some apps, various Safari tabs weren't even rendering, and my computer fan was whirring/purring faintly. That's all well and good, because I force quit everything, and when that didn't help completely, held the power button and shut down my computer, only to find that when I powered back on my computer it still was hot and stuff.
I guess my question is, does leaving your computer screen and applications on for a long time make it complain and it will still be laggy and hot and stuff even after you terminate all processes? Or is my computer just getting old so I have to buy a new one in which case tsk tsk Apple. I have a Early 2014, 13" MacBook Air.