The GW2 system requirments just mean ’ you can run the game’, not that it will be playable. Thats what reccomended specs are for. . and notice that Anet have no reccomended specs ..becouse they are really high and requir OC’s ..which ofc they cannot recommend people do for obviose reasons.
The reason for ur performance monitor not showing 100% is explained here.
https://forum-en.gw2archive.eu/forum/support/tech/FAQ-Frequently-Asked-Questions-Compilation/first#post1095383
Bassicaly Your CPU is split into core’s and threads, when all are used up .u have 100% usuage, BUT if 1 of those cores/threads maxes out when processing one of GW2’s 50 odd threads, that causes all other GW2 threads/processes to slow down to match it.
The main GW2 thread is very intensive, once that maxes out(meaning ur CPU is procesisng it as fast as it can) all other GW2 process cannot be run any faster than that parent thread.
This means you get a FPS drop, and also means u wont see 100% usuage on the CPU becouse not all the cpu’s threads are being maxed out,, only that 1 is, the rest are running a what ever usuage it needs to run the other Gw2 processes that have been slowed down.
AMD cpu’s have slower single thread processing power, which is why they r not the best choice for gaming in these intensive CPU situations, however most games are not as intensive as GW2 is on the CPU ..so u generaly dont see it untill extreme situations. GW2 on the other hand is intensive throughout, so when things really get busy like in WvW ..CPU’s single thread performance gets tested hard. This is why even with a top of the line Intel CPU .. u need to OC them just to keep FPS above 30 in WvW.
http://www.cpubenchmark.net/singleThread.html
This is a list of the single thread performance of all current CPU’s . Note they are all on stock and none of them at stock can keep WvW in GW2 from droping below 30 in heavy situations. So those CPU’s way down the list are even more at a disadvantage.
Since GW2 is so intensive on the CPU , so long as u have a good OC on a 2nd/3rd gen intel i5 or i7 u dont actually needa very good GPU, however alot of people are having performance issues when using the laest series of graphics cards, hence why u may see now and then people complaining about bad performance even with high end rigs, its usualy drivers issues or settings ingame, nothing to do with their CPU.
In ur case i think its the CPU, since graphics settings r doing little to imporve ur fps, and the fact it gets so bad in WvW.
BTW my rig aint all that atm, the graphics card is old .. and my CPU is no better than a 3570k/2500k with OC in ‘most’ games. I built my rig for more than just gaming ..hence the expensive CPU