I strongly recommend launching DCS World from PiTool only one time, and only if needed to eliminate the need for parallel projections or prevent inexplicable double framing.
My experience running DCS World through PiTool has been that it is extremely buggy, triggering a few error messages. Doing this at all is very likely no longer necessary for any reason, but at one time, it changed something about DCS, the graphics drivers, or some unknown magic, improving performance thereafter, regardless of whether DCS was launched from PiTool.
Personally, I just use a checklist spreadsheet, manually setting everything before launching simulator apps. Until PiTool supports command line parameters so things can be set by macro/batch script, I think this is the best that can be done for anything that runs under SteamVR.
You may get better results by ‘overclocking’ your RTX 2080 Ti. Unlike CPU overclocking, these GPUs simply aren’t clocked to their safe limits out of the factory. Most can reach >2000MHz without doing anything that has any chance of breaking a good condition card, voiding warranty, etc. Should be as simple as downloading the program your manufacturer provides, setting voltage and power target to max allowed, and setting core clock to something like 1975MHz for starters.
That said, if you really want to diagnose this further…
First, please ensure you have provided, all of the exact error message. A screenshot would be preferred. Quick google search turns up nothing DCS World relevant, though this at least confirms it is possible a ‘hello world’ LUA script entry is lurking somewhere - http://www.unrealsoftware.de/forum_posts.php?post=400667 .
Next, disable all modules (aircraft like FA18C, FC3, etc), especially any with any kind of DRM. You can enable them one by one later.
You might also try installing the stable or openbeta version of DCS World.
Moving relevant Saved Games folders, and uninstalling any mods, may also resolve this, since a LUA script may be responsible.