Overnight Microsoft released Flight Simulator X Service Pack 1.
I am certain that this will address many of the performance issues that people had with the game, and I am also certain that (as always) there will be people that complain that their favourite airport or aircraft didn’t get something fixed 
Remember… this is a performance update and there will be more updates to this version ongoing as the team have said time and time before.
Phil has also posted the following articles on his blog that I strongly recommend you read:
Preparing to Install
Aircraft Scenery Fixes
Missions, Multi-player and Misc Fixes
SDK, SimConnect and 3rd Party Fixes
Performance Work
New Tweaks
To the ACES team…. congratulations, I know you worked your arses off on this update!