Hello.
- Clear cache at least twice a day: Press and hold the power button until your turns off.
- Make sure you have 500MB free internal space.
- Use a lite Browser like Opera mini.
- Disable images on your browser.
- Set network mode to 3G or auto.
- Uninstall useless apps most special apps that can run in background (social apps).
- You can also look for any internet speed enhancement apps from Google play store.