My Iphone 5S is getting slower and it freezes very frequently. Software is updated and 4GB is free. Kindly advice

Hello Tsharma21,

I understand that you're experiencing some issues with the performance of your iPhone 5s. I know how frustrating it can be to watch a once sprightly device gradually slow down. Fortunately there are a number of steps that can help restore your iPhone to its once nimble self.

Force an app to close in iOS
http://support.apple.com/en-us/HT5137

Turn your iOS device off and on (restart) and reset
http://support.apple.com/en-us/HT1430

If your iPhone continues to perform slowly or occasionally stop responding, the next step would be to reinstall iOS on your device by placing it in Recovery Mode, then choosing Update in iTunes. Prior to doing so, it's always a good idea to make sure that you've got a backup made.

1. Make sure that you have iTunes 12 or later on your computer.
2. Put your device in recovery mode.
3. When you get the option to restore or update, select Update. This will reinstall iOS without erasing your data.

If your iPhone, iPad, or iPod touch doesn't respond or doesn't turn on
https://support.apple.com/en-us/HT201412

Sincerely