In the time between, the current release build is now 6196. I was referring to the previous release at 6174, which is
available in the archives. You are right, it is possible someone else did suggest the Dev build as various fixes may be in it, that are not yet released. In this case it is a bit of trial and results to see whether it works fine in one build and not the other, so it can be narrowed down to see if it was a recent change which is affecting you, or whether it is just something else.
The something else is usually some other software that is running. The most common of which are overlay (or On Screen Display) type things. The other ones that tend to cause performance hits are anti softwares, which end up blocking or scanning as the programs run (although the default MS Defender/SE normally doesn't cause this kind of grief).
As for STO via steam. I mean it was loaded out of a steam library folder structure (D:\SteamLibrary\steamapps\common\Star Trek Online\Star Trek Online\Live\GameClient.exe). The last time I installed from Arc, it didn't put it there. Sometimes installing steam versions, means that Steam will be hooking the game as it loads, which might cause some oddities.