This little trick should help you play some of OFPEC's bigger missions with less lag.
Load up Flashpoint, and then alt+tab back to the desktop.
Control+alt+delete to get the task manager, then go to processes. End the explorer.exe process. Then go back to Applications and Switch To back into Flashpoint.
You should get more performance.
Once you're ready to end the game, quit normally, then open task manager again and go to File. Click New Task (Run) and type explorer.exe.
Finished.
I don't know if its dangerous to do this but it works for me.
Also, you can quit other processes you won't need for playing the game. Its up to you what you keep on.