Turn Windows features on or of

This de/install Windows programs.
In general a program won’t do any harm if you don’t start it.
De-installing probably won’t make much sense.
It won’t do harm either, you can always re-install them.

I simply deinstalled them all.

Index server

Disabling the Windows Search removes the search box from the explorer.
Enabling it brings back the search box in the interface but searches don’t work.
This requires the Indexing Service to run.
This generates a lot of I/O.
You can limit this by choosing the directories to be indexed.