Improve performance of automatic environment detection

[DonJayamanne]

When extension loads, it attempts to automatically set the workspace interpreter.
However this slows down the load times of the extension.
Optimizations: manually construct VirtualEnvService passing in the current workspace.

[Yensan]

Hi, @DonJayamanne , I don't think detect python env is a good decision. As an user I always set the env by myself. Maybe there are so many python: (2.x OR 3.x) * (32bit OR 64bit) * (install OR virture env)
But performance and intelisense is not very well in vscode-python:

• it will cause break or zoombie to vscode and windows
• intelisense for import expression such as import sys. , and if a package is import, the class/func/var can intellisense in that file.

[DonJayamanne]

Please create a separate issue for performance issues faced in intellisense. If you are experiencing performance issues with auto detection of the interpreter, them please create an issue for that as well.
The decision has been made to improve the ux for the user by auto detection the virtual env, and we believe this ux can be improved further. Hence this issue.

But performance and intelisense is not very well in vscode-python:

So please create issues for this with some measurable data.

As you can see we are taking steps to improve the performance around intellisense with PRs such as the following: #368