Hello baron28,
From your post it sounds like you are having a variety of issues.
The first thing you want to check is that the Mac has enough free hard drive space to operate. It is important the the startup drive have at least 30 GB or 15% available free space. You can find ways to increase disk space here: How to free up storage space on your Mac - Apple Support
Check to make sure that all software is up to date: How to update the software on your Mac - Apple Support
Start up the system in safe mode. Starting in safe mode forces the computer to run some disk checks similar to First Aid. This can resolve some issues. To start in safe mode, begin with the computer powered off. Follow the directions found here, depending on what type of Mac you have: How to use safe mode on your Mac - Apple Support
The computer will take longer to start in safe mode, and the screen may have some distorted video as it starts up. This is normal. Once you are logged in, restart the computer normally and check the performance.
You can also reset the SMC. The SMC is responsible for managing behaviors related to multiple systems. Instructions to reset are available here: How to reset the SMC of your Mac - Apple Support
Next reset the NVRAM. The NVRAM (nonvolatile random-access memory) is a small amount of memory that your Mac uses to store certain settings and access them quickly. Reset NVRAM or PRAM on your Mac - Apple Support
Let us know the results.