I have a similar problem, I used to play on my old Asus laptop at max graphics with no problem, at least 60fps all the time. Sadly that was a few years ago, I recently got a new desktop and I loaded GW2 after it became F2P so I could help some of my friends who wanted to start a character for the first time.
Long story short my hex-core cpu and Titan X can’t run this above 43FPS on lowest graphics, something is very, very wrong. The only time this rendering beast has gotten lower than 60FPS on anything is Star Citizen on Very High graphics. (I do graphics work, so I needed a rendering machine. That’s the excuse I tell myself at least)
Hopefully someone finds a fix or at least a cause for this.