ActionScript 3.0 :: FrameRate Changes To 1 When Deactivated?

i am making a flex air application and when its deactivated (lost focus), its framerate becomes to 1fps.i am using psudo-threading encoder that uses enterframe to keep it working the app requires long time converting process more than hours and i need the program to do the same thing while sitting back in the background how to disable deactivation in air application as soon as the focus is out, it becomes 1 fps instead of 24 fps which i need.

i know i can use timerevent rather than enterframe event but my app needs alot of calculation and i figured that in flash, the frame extends its time if the calculation isnt finished. if it gets too long in one frame, the ui hangs up.if i use enterframe, on slow comps it would extend its time to complete the calculations when all the calculations didnt get to finish in time in 1 frame.but im afraid if i use timer event, instead of waiting for the codees to be excuted it would excute the next timer event, i didnt try it though.i created the app that when you add the xml songbook data, it would load up the data sort it and create pages with the graphics and skins set up and when you save, it saves the pages to jpg files using the encoder i created.and the encoder uses enterframe.its working fine but when i deactivate the window while encoding, it becomes extremely slow since it becomes 1fps.