Please note that the commands will only work on Windows 8 or newer machines.

Here is what you need to do to analyze the WinSXS Folder:

1. Tap on the Windows-key, type cmd.exe, hold down Shift and Ctrl, and hit the enter key on the keyboard. This opens an elevated command prompt on the system.
2. Run the command dism.exe /Online /Cleanup-Image /AnalyzeComponentStore
3. 

The parameter /Online refers to the current installation, and /Cleanup-Image /AnaylzeComponentStore to analyzing the current component store of that installation (the WinSXS folder).

You can list all available commands using dism.exe /?, and subsequently dism.exe /Online /? and dism.exe /Online /Cleanup-Image /?.

The command runs a scan that takes a moment to complete. It echoes the Windows Explorer size and actual size to the command prompt window, and gives recommendations whether it makes sense to run a cleanup operation.

Cleanup

Windows runs a cleanup regularly using the Task Scheduler. You can check if that is the case on your machine in the following way:

1. Tap on the Windows-key, type Task Scheduler and hit enter.
2. Navigate to Task Scheduler (local) > Task Scheduler Library > Microsoft > Windows > Servicing > StartComponentCleanup

You can run the cleanup operation manually at any time using the following command using an elevated command prompt:

dism.exe /Online /Cleanup-Image /StartComponentCleanup

or for more

dism.exe /Online /Cleanup-Image /StartComponentCleanup /ResetBase

For service pack cleanup

dism.exe /Online /Cleanup-Image /spsuperseded /hidesp