I've also had this problem. I created a new project based on an existing database. Opening the project in VS2019 leads it to hang at the "will be ready" phase and consumes so much system resources that I have to close VS.
Other notes:
- I have installed VS2022 and experience the same issue.
- I've installed the VS Code extension "SQL Server" and the project hangs during "Building the project model" step.
- Apparently, the VS Pro subscription does not include support for this. I can only speculate it's because it depends on SSDT in the background.
Overall, it appears the MS's tools in this area are an absolute failure and this bug has been around for almost a decade.