Super low FPS on old game????

Shaiya is a super old dx9 mmorpg.
I have i5 10400f rx 6600 tx 16 ram 2400mts (old)
I can play a lot of titles on high settings, I struggle with games like rust due to memory (i think)
but shaiya it’s just nonsense, i’m in pvp a lot of characters and i get 20 fps, barely any gpu/cpu usage.
I got a fullscreen dx9 error that got fixed when i disabled the optimization, also tried vulkan but didn’t change much.
I don’t know what to do.
Also anyone knows why my cpu says 2.9ghz when I have turbo boost enabled and it should be 4?

tyty