The new PHP7 version has lots of improvements, compared to the old PHP5. PHP7 uses half of the memory and its performance has been improved significantly. Here are some other benefits of using PHP7:
- PHP 7 is almost twice as fast as lower version of PHP
- Low memory usage (up to 50%)
- Facilitates Error Handling
- 64-Bit Windows Systems Support
- New Spaceship and Null Coalescing Operators
- Enables Accurate Type Declarations
- Add Anonymous Classes
- Facilitates Imports From the Same Namespace
On the other hand PHP5 version will not be supported for much longer. These are only couple of reasons, but you get the point.