The Galaxy Light was designed as a second-tier phone for people who didn't want to pay $700 for a S5. It has a slower processor and half the RAM of the S4, so in terms of the flagship devices for Samsung, it was built with capabilities to perform somewhere between an S3 and and S4.

I still have 2 S3's that are in use on a daily basis in my household, and they're still perfectly capable of handling anything you want to do with them. Samsung's Touchwiz interface and add ons to the stock android OS are designed around the phone's hardware. The software package for the S3 still operates very well because it was designed around the specific hardware capabilities.

The Galaxy Light, despite having hardware more in line with an S3, has a version of Touchwiz that was derived from the S4 OS. If you recall when the S4 was released, there were lots of complaints about the big, bloated, operating system that Samsung used that took up a huge chunk of the phone's available storage. The S4's OS is the worst designed OS of any of the Galaxy phones to date.

Unfortunately you have a derivative of this bloated OS on your Galaxy Light. On top of that, the OS was designed for the more powerful S4. As a result, the Galaxy Light tends to be glitchy, freeze, and is prone to random reboots.

I'm sure there are stripped down ROMs for the phone. I'd consider rooting and installing a stock android. This would go a long ways towards fixing a lot of the problems.