To start the debugger, press Ctrl + F7
You will have an histogram in the middle of the screen, and a little window in the top left corner:

When you have a micro freeze, you will have a slightly higher bar, click on Paused: False to freeze the histogram.
(Press Alt to unlock the mouse in game)
When the histogram is stopped, click on the highest bar to show the detail:

You can click on a second bar to get a comparison:

Press F10 and go to MyDocument\ManiaPlanet\ScreenShots folder to get the screenshot.
Profesional tips / Advanced tips: These tips are for professionals and for bugs, issues, micro-freezes that can help advance the game-developers.
Press F12 and you will see information about CPU Usage aswell as GPU Usage:

Press Ctrl+F11 3 times to get the following window:

It will show the TCpu or TGpu. It will help Nadeo to see if it is a CPU issue or GPU one.
Press F10 to make a screenshot or do a printscreen and save it in Paint or any other graphic design tool and save it in a webformat like a .png or .jpg.