Ive had this issue since I think the Vanguard patch and figured out what causes it. Whilst trove is running, a program by trion called "Crashhandler.exe" is running attached to trove. I was out of ideas on how to fix this and the support wasnt able to help me aswell so I tried killing the process
and boom, no more fps dropping or crashes since I did that. I also found an permanent fix for this and im gonna share it with you to hopefully fix this issue for you aswell

Steps:

1.press Win+r
2. type; "gpedit.msc" without " and press enter
→this should open a window, if it doesnt and it says that the programm doesnt exist or similar,
google on how to install it.
3. After you are in there, click on "Local Computer Policy -> expand "Computer Configuration ->
expand "Windows Settings" -> expand "Security Settings" -> expand Software Restriction
Policies.
→If you cant expand it yet, right click on "Software Restriction Policies" and click on create
new policies
4.If you did it right, there should be an entry called "Additional Rules", click on that one once.
5. Right click into the part of the window on the right and click on "New Path rule..."
6. Click on browse and go to the path of the crashhandler.exe and select it. (its located in the
same folder as your trove.exe)
7. Keep everything else on default, click on apply and close everything.
→ What this does is it prevents the crashhandler from starting when starting trove.
8. The drops and crashes after dropping fps should be gone, I hope this fixes your issues

Yours Criteox