If official drivers are unavailable for your version of Windows, software like Snappy Driver Installer or Device Manager (via Hardware IDs) can help locate generic drivers for components like Atheros Wi-Fi or Realtek Audio. Key Drivers for Sony PCG-31311L (VPCYA1AFX)
If your hard drive is intact and you have not wiped it, you can reinstall original drivers by accessing the VAIO Care tool and selecting "Reinstall applications and drivers". sony pcg31311l drivers
Simply put, if your PCG31311L is running slow or erratically, outdated or missing drivers are likely the culprit. If official drivers are unavailable for your version