Trying to solve noticeable autocomplete slowdown in Luau LSP

[JohnnyMorganz]

Users of Luau LSP report a noticable autocompletion delay for the following code, specifically when the return type : boolean is explicitly stated (JohnnyMorganz/luau-lsp#304):

local function a(): boolean
  return t|
end

Diving deeper, I find that the slowdown is in the autocomplete's checkTypeCorrectKind, specifically on my Instance global (it takes 1.04128s to return in release mode)
Looking into the unifier, it seems to come from the following code:

void Unifier::tryUnifyScalarShape(TypeId subTy, TypeId superTy, bool reversed)
{
    TypeId osubTy = subTy;
    TypeId osuperTy = superTy;

    if (FFlag::LuauUninhabitedSubAnything2 && !normalizer->isInhabited(subTy))
        return;

Particularly, the normalizer->isInhabited(subTy) call, where subTy is the Instance global (and superTy is the Boolean primitive type).
Is there anything I can do to improve this situation?

For reference, the Instance global is defined as https://github.com/JohnnyMorganz/luau-lsp/blob/d5ccc835fcdccc1d25f71bc51f324b423383a806/scripts/globalTypes.d.lua#L9703-L9705, and the only extra processing I do is attaching a magic function to it (https://github.com/JohnnyMorganz/luau-lsp/blob/d5ccc835fcdccc1d25f71bc51f324b423383a806/src/LuauExt.cpp#L462-L471 and https://github.com/JohnnyMorganz/luau-lsp/blob/d5ccc835fcdccc1d25f71bc51f324b423383a806/src/LuauExt.cpp#L279-L290)

I assume the problem is the significant amount of function overloads for Instance.new

[vegorov-rbx]

I'll check what's happening here.

[vegorov-rbx]

We should have a work-around for this issue in the next release.

For the current version, situation can be improved by lowering the value of LuauNormalizeCacheLimit or by removing large function type overload set and implementing the behavior using a magic function that returns type based on name.