When you post you may want to "be sure to include all your system info, including operating system, model number, and any other specifics related to the problem. Also please exercise your best judgment when posting in the forums--revealing personal information such as your e-mail address, telephone number, and address is not recommended."

Given so little detail the only advice would be to reload the OS and see if the speed returns but that seems harsh and un-needed in most cases unless the OS has suffered deep damage.
Bob