If the laptop is using a hard drive as opposed to an SSD, then the hard drive is failing if the noise is coming from the drive. You can replace the hard drive with an SSD which would boost the performance a bit. The best SSD options would be a Crucial MX500 series SSD or an OWC Mercury Electra 3G SSD. Other SSDs may work, but compatibility is not guaranteed with an older Mac since this older Mac utilizes a SATA II controller which is not always compatible with SSDs using a SATA III controller since they have difficulty negotiating the SATA Link Speed.
The OWC 3G SSD is the best option since it uses a SATA II controller so there should be no issues negotiating the SATA Link Speed. I have used the MX500 SSD in some of our organization's 2010 Apple laptops.
Avoid the Crucial BX500 series SSD as they are junk which can be just as slow as a hard drive and they tend to overheat very easily and also have a high rate of failure.
The only reason I'm even suggesting this is because this SSD can later be used with any other computer if you get a USB to SATA Adapter, drive dock, or enclosure. So the investment is not completely lost if this laptop is retired.