At 1.4 GHz, your CPU is pretty slow by today's standards. You can do a C-A-D, start the Task Manager to see which tasks are using the CPU. To do that click the processes tab, then click the "Show processes from all users" button. Fiinally click the CPU column heading TWICE. This will show a list of active tasks sorted by the largest users. If you have some rogue task gobbling up all the resources, you can click on it, then click End Process. Be careful not to click tasks that are critical to running Windows or you'll crash & have to reboot.

Good luck.