Starling is a great framework. It has fallbacks. Chances are you're either trying to do too much at once with too high of an expectation of ipad1, or you're falling back to CPU blitting.
I struggle greatly with ipad1 with CPU blitting myself. But lets not compare in an unfair way. iPad1 comes with a single A4 processor. iPad2 comes with more memory and dual core A5 processors. Wednesday they may be debuting iPad3 with who knows what, dual/quad a5x? Dual/quad A6? They're going to need a good performance bump (CPU, GPU (mostly)) if they plan on rolling out retina.
The performance of CPU blitting between ipad1 and 2 is night and day. It's almost silky smooth on ipad2 but it's border line acceptible on ipad1.
The GPU is a PowerVR SGX 543MP2 on the ipad2 which Apple claimed was 9x faster. Is it any shock it's doing better with Starling or Stage3D?
I'm in your boat in desiring to put ipad1 to bed. I hope ipad3 will open the door for that pretty soon. But bottom line, if you really want ipad1, you're going to need a fallback. Starling has that, but if you do 'too much at once', ipad1 will surely die. Perhaps how much you do at once needs a code branch specifically for ipad1 to assule you don't do too much.
