I am using cobra with 7" display…I had quite a bit of flicker & found the regulator IC1 is quite hot, even with 6.1v input. When lowering the input down to around 5.5V, the flickering stops, but the regulator is no longer regualting (puts out 4.5V)…you need at least 6.2V at “no load” for it to put out 5V.
At 800ma, the regulator requires 1.2V headroom, but runs too hot.
This design needs better heatsinking or a larger regulator