"100% of at least 1 CPU USAGE" Help Plixx

I want to know why does almost every day i get the same msg. 

when im play a online game name (TIBIA) and it makes me go slow sometimes

and when i get this msg i get nervous why does it do that.

 

i have a 

w8 

intel(R) Core (TM) i5-3470 CPU @3.20 GHz    3.60 GHz

ram 8gbs 

1tb of memory