How are the dual encoders attached to the Uno? I only see two encoder pin inputs in that code. Are they both attached to the same encoder?
This suggest detailing the connections with a schematic:
From the code it looks like the counting is only counting up. Is that good enough for speed? If you don't need actually direction information counting up is simpler and quicker.
Does the code compile? I see that a semicolon is missing within the pulse_counter_B() routine.
I'd move this line out of the pulse_counter() function and into setup() because it doesn't actually change anything after the first invocation:
You also should not print within the interrupt service routine, since it can cause problems.
Alse, since count and count_B are set within interrupt service routines, when they are used elsewhere, you should make a safe copy that won't be corrupted if it happens to be changed while it is being used:
noInterrupts();
int safe_count = count;
int safe_count_B = count_B;
interrupts;
And with speeds like 3000 RPM and an encoder with 10 slots (20 CHANGES/rev) it would overflow an int in 32767/(3000*10*2)=0.27 minutes. You should probably use "long" or "unsigned long" declarations for your counters.