You can open large codebases in Jetbrains IDEs and it takes forever to index, but it shouldn't outright crash or completely freeze.

You can open the kernel in CLion. Don't expect the advanced refactoring features to work, but it can deal with a ~40 million lines project folder for example

IntelliJ IDEs are fine with huge files and projects. At certain sizes it'll disable intellisense in active files, but IME stuff like find and replace works fine regardless of size and you can still turn intellisense on if you want.

They'll index for a long time on huge codebases, but I only go through that like once a month max, I just have the editors as always open