There are some simple tricks that can make your computer faster. It does not matter that this is Apple, Windows or some other operating system. Feel free to try them on your hardware.
The operating system power scheme ajdust components speed according to the system needs. In the most time when computer is on and you are doing nothing on it, the power controler tries to minimalize power consumption of cpu, graphics card (if integrated) and other components. Sometimes it does not work like we would like it to do. If you set the default system power scheme to maximum (or "Full Power") at all time your computer system will be always ready to respond on your task as fast as it can. Note that it can grow up the power consumption.
When using mobile computer without power adaptor connected, the operating system can slow down the hardware parameters and operating system will work slowly. This problem can be simply fixed by connecting the power line. The power scheme will maximize hardware parameters when of course the step 1 is done.
This is the simplest solution. The applications that are run in background and not used at the moment consume system resources like a RAM memory and a CPU time. Of course you can install some additional RAM, buy a fast SSD disk or you can simply close the unused application :)