Excessive CPU usage with https://github.com/dotnet/runtime

I'm experiencing this in my linux development VM for https://github.com/dotnet/runtime, running a VS Code client on Windows connected to the linux host (so cpptools runs on the linux host along with some node processes, while the UI runs outside of the linux host). Has any testing happened with that repo for this issue? It does seem to be much worse during builds, which is confusing because I got the impression that vscode takes gitignore into account for these things like it does for project-wide search and build artifact directories are ignored.

When I checked in and opened top, cpptools' cpu time total was around 65 hours, with xorg and konsole at 23 and 21 hours and node (probably the cpptools parent?) at 19. cpptools also was using about half a gig of memory (2.4g virtual).

Originally posted by @kg in https://github.com/microsoft/vscode-cpptools/issues/5574#issuecomment-791321351

No file, test, or code entry point is named. Start by reproducing the Linux development-VM setup with VS Code connected from Windows, then observe cpptools and node CPU usage during builds. Done means identifying the cause of the excessive CPU use and verifying that usage is reduced in the reported workflow.