Lagging in WvW/Big events

Hey, I was hoping I could get some help on figuring out what is causing lag when I do WvW/big events even on lowest graphics. My dad is adamant my CPU is fine, though I've heard in a lot of lagging cases that it's because the CPU needs upgrading. But I'm no good with computers and my dad does the upgrades, I do plan on learning more.So, here are my specs, any idea on what could be causing lag and issues? And what would be good to upgrade to allow me to play WvW without constant lag and FPS of like 10, when in large battles even with lowest graphics.Processor - AMD A10-5800k APU with Radeon HD graphicsInstalled RAM - 16.0gbGraphics Card - NVIDIA GeForce GTX 750 TiI currently run GW2 on an SSD as well for load times and still have 80-ishgb available on it.I'd like to get a new graphics card as well so any recommendations would be great!

Thank you in advance :D