Before you start any level, make sure you unequip any armor and weapons/gadgets you may have. If you did it right, mobility should be 100% and noise should be at 100%.

When the run starts, quickly knock these 2 guards out, make sure you are at maximum speed

Run past the glass window, but don't knock out this guard until they are about here, you need to do this to save time later

If you did this right, this guy should be about here and you'll be free to just run past him, make sure you close the door so he doesnt ruin guard patterns.

Break the lock on this door, lockpicking is too slow, and make sure you close this door behind you

If you did this fast enough, this guy should be coming right at the door, knock him out when he opens it and run directly upward

From there knock out this guard and keep heading up
Vault to enter this room and wait for this guard to open the door, then knock him out

Enter this room and skip the cutscene

Run back the way you came and break the lock on this door

From there, continue to run the same way back and break through this window before vaulting through it

After that, you can run to the exit of the level.

A clean run of this level should look like this

This section relies far more heavily on speed than the last one, if you are too slow you will not be able to preform these tricks.

When the level begins, immediately run all the way up the level and knockout this guard

Run down and to this guard and knock him out, then keep going past him

Run quickly past the light and knock this guard out, if you're too slow you will be seen and killed.

Run down and bum rush this guard. There's a VERY slim window to where you can hit him without being shot

Stay on the RIGHT side of this corridor or you WILL be seen by the camera operator, this isnt recoverable.

Run down and knock out this guard. The guard below him should hear it.
Wait for the guard to open this door and then knock him out.

After that, head down, break the lock, and skip the cutscene.

After all this just follow the same route back, remember to stay on the RIGHT side of the corridor when passing the boxes again.

A clean run should look like this.

This is how you trivialize this difficulty, have fun!