When I refer to precache errors, the line below is what I mean:
Attemped to precache unknown particle system "<particle>"!
Context: So I've heard online that console errors tend to reduce fps. I have not fact checked this rumor of course, but I still wanted to get rid of them. For a while, I was trying fixes that ultimately were not working.
Then I learned that TF2 stores some graphics cvars in the Registry (Keys Computer\HKEY_USERS<id of some sort>\Software\Valve\Source\tf\Settings and Computer\HKEY_CURRENT_USER\Software\Valve\Source\tf\Settings specifically), so I start setting each convar to 0 and running tr_walkway_rc2 to check whether the precache errors stopped. Eventually I set mat_reducefillrate to 0, and the precache errors stopped.
Currently I am looking through the source code leak of 2020 to figure out why that cvar would cause them.