As far as I know, database applications use CPU and they depend on the CPU to load and perform all the operations. It won't help if you close or uninstall other applications installed on that PC. The PC needs an upgrade in terms of physical hardware. You will need to replace the CPU with something more powerful, and as you're at it, install some more RAM as well.
There isn't much to do when it comes to SQL servers. You either upgrade the PC or run it in the current form.