FSPS - FSX FIBER ACCELERATOR
It really works well. It's still new at the moment, so I'm sure that in the near future, they will come out with updates to increase performance even more. For some reason I got a OOM message for the first time in ages after testing out a bunch of different scenery. Clouds still kill FPS, but at a busy and highly detailed airport, with the PMDG 777 running, FSX is silky smooth. I'm very impressed with this program.