cpptools takes hours of CPU time per day for a project which compiles in 5 seconds

Type: LanguageService

Describe the bug

• OS and Version: OSX 10.15.4
• VS Code Version: 1.45.1
• C/C++ Extension Version: 0.28.1

For every C++ project, even tiny ones which compile in a few seconds, a cpptools process runs for something between 6 and 40 minutes every time I open the project and also from time to time after editing or git operations. Over the day this accumulates to many hours and estimated about 25% of the time my laptop fan runs cause of cpptools (it hardly every runs cause of compiles). Also the memory consumption of cpptools is fairly high - around 7GB is common. I guess this has to do with scanning system headers, but is still seems wasteful to spend 30 minutes on symbol analysis for a project where a release build takes 5 seconds. This is not really a bug, but to me it looks like unnecessary waste of resources.

One more observation: when I delete the folder in which VSCode keeps the database (on Mac ~/Library/Application Support/VSCodium/User/workspaceStorage/) it runs the first time "only" for 6 minutes - Intellisense is fully operational. The second time it decides to run for the same projects - about 1 hour later - it runs for 29 minutes.

Steps to reproduce

• Open any project with C files
• Look at the CPU time of the cpptools process

Expected behavior

• cpptools needs less than 10x the compile time

In case you cannot reproduce this (for me this happens for every C++ project every time since at least 6 months) I can of cause provide logs, a sample project and gprof statistics.

Start by reproducing the issue with a small C/C++ project and inspect cpptools CPU and memory usage, including the workspace database behavior described for macOS. Review the available logs, sample project, and gprof statistics offered by the reporter; done means resource usage is reduced toward the stated expectation of less than 10 times compile time.