Three issues:
1. You are using integrated graphics (That's what an APU is - a big "no no" for gaming like this)
2. You have a normal hard drive disk (they fail easily) Also if it is over 50% full it will take a significant performance hit (causing loads to be long) gets worse the fuller it gets. (SSD don't have this issue that people can notice.)
3. If you don't have space for a normal PC I can assume you are using wi-fi. Wi-fi will also add to the lagginess.

Personally if you have the money I'd drop it on something portable geared towards gaming. (Although I hate "gaming notebooks")
However this is a costly option; this is not something you can cheap out on and not expect something that performs poorly.