F2P MMO help

[Saika Darkmoon]

Hey I am looking for a good MMO to play, i think Tera would be too much for my PC and i for now have an actual windows PC. My specs are as follows.

Processor: AMD E1-1200 APU with Radeon HD Graphics 1.40 GHz

RAM: 4.00 GB (3.60 GB usable)

System Type: 64-bit windows 7 OS

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So far i have tried Rusty hearts, Elsword, Persona ( the online one ), and Vindictus.

Vindictus: Fail even on lowest settings it was super slow.
Rusty hearts: awsome when playing solo in a dungeon, super slow in towns.
Elsword: Minor lag ran smothely.
Persona online: PERFECT even on highest settings.