In my experience the setting that has the biggest impact in the game is character model limit
You can lower your shadows, shaders, reflections, texture quality etc to low or lowest but if you leave character model limit to high values (medium, high, highest) you won't get decent fps..
Character model limit is the amount of people you see on screen, during big events this is the main cause of low fps because the game is processing all the people on screen therefore all the shadows, particles, light effects etc coming from all those players, that kills performance in some computers.
Try this:
Character model limit to medium, low or lowest, the lowest value gives the best performance but hides most of the player characters around you and gives them a default appearance.
Character model quality probably to medium, i doubt that low or lowest will increase the fps. This is the quality you will see from other players around you, not your own toon.
Shadows to medium or low, you won't notice it after a while
Reflections to NONE if you truly struggling with fps, The reflections have a big impact on performance, see how much fps you get with "terrain & sky" setting but if you want more fps just pick "none"
High rest textures and high quality characters can be set to HIGH so you can see pretty models and not pixelated, low res characters. Some people play with this option to lowest thinking that it will improve the performance while ignoring other options like character model limit or shadows which hit performance much more.
best texture filtering to high/on it doesn't impact that much like other options, and makes the game looks better.
Shaders to medium, some people prefer it anyways, because high shaders give this "shiny" appearance and not everyone likes it.
FXAA antialiasing.
Let us know if this improved your FPS, sometimes fps get better when you delete the gw2 cache folder and the local.dat file when it gets corrupted, the launcher will rebuild both next time, you can google it like "gw2 local.dat file" to get more info. Also use windows defender and perform a scan in your computer, who knows maybe you got a bug as in virus draining your resources and then all the windows 10 and windows 11 bloatware eating ram and cpu, that's another topic but there's plenty of telemetry and useless options everywhere,