Quadrature encoder - bad counting

I am trying to interface high resolution quadrature encoder AEDA-3300 with 4096CPR which means it has 16384 PPR I tried codes from Playground for reading rotary encoders and come up with only around 500 counts per turn using first example and around 1000 using interupts using second code. I am rotating it with figers reallly slow and it still has this low counts. Encoder can work with 12000 RPM so there is not the problem Any ideas?

I got it... printing to serial port makes it slow but it counts correctly. I just put in main loop to print every 100ms and I get correct results cheers