Quadrature encoder - bad counting

[nekodrugi99]

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?

[nekodrugi99]

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