It's one of the Visual Studio 2022 components. This one is responsible for resolving types/symbols and providing GitHub Copilot.

From what I noticed, it's likely to use lots of memory if:

1. You have many lines of code in one source file,
2. You're working on a partial class that has a large sum of total lines of code

Killing it is fine - by doing so, the process will immediately restart with lower memory usage, and almost nothing will happen, except that it will crash GitHub Copilot until you restart Visual Studio.

If feasible, I'd recommend splitting one large source file into multiple classes (up to 1000 LoC each), as that's lesser symbols to resolve.

See also this answer.