I just have downloaded and installed the Performance Visualizer Extension, have selected the desired Visualizer Names in Tools - Preferences - Performance Visualizers, have restarted WL6, but the tabs don't show up. What am I doing wrong?

I don't know what you're doing wrong because there's no information. Yes, I mean something else than "not enough" - not at all.

Which visualizer library have you downloaded? There are 3 (three).
Which desired performance visualizers have you selected?

What position sizing is selected?
Which mode the Strategy is running in, single symbol or multi-symbol?

Finally, keep in mind that selecting a visualizer does not apply to previously saved workspaces, including Default workspace. Strategies in workspace always load with the visualizers enabled at the time of saving the workspace.

I cannot know beforehand what information is needed as these extensions are new to me. I have done exatly what was written in the instructions, namely:

QUOTE:
After installing this Extension, enable your new visualizers in Preferences > Performance Visualizers

That's all there is. Nothing about workspaces. Then I missed all the new tabs.

It was the workspace thing. Thank you.

You're welcome. Glad to have helped.