Well let's see what we can do here ...

Since it's an 18F, with "qualified" ASM handlers ...
You can remove the remaining overhead by removing DT_INTS all together, and using an ASM ISR, written in PBP of course.

Something like this ...
Code:
DEFINE INTHAND _ISR
DEFINE NO_CLRWDT 1

;---------------------------------------------------------------------------
ISR:
  IF INTCON3.1 THEN             ' IF INT2 triggered
DoStep:
    If PortB.1 = 1 THEN         'Direction signal connected to PortB.1
      Setpoint = Setpoint + 1    'Setpoint is a 32bit variable
    ELSE
      Setpoint = Setpoint - 1
    ENDIF
    INTCON3.1 = 0               ' clear the int flag
  ENDIF
    
RollOver:
  IF PIR3.2 = 1 THEN            ' if IC2QEIF triggered
    IF QEICON.5 = 1 then
      Position.Word1 = Position.Word1 + 1    'Position is a LONG
    ELSE
      Position.Word1 = Position.Word1 - 1
    ENDIF
    PIR3.2 = 0                  ' clear the int flag
  ENDIF
@   RETFIE FAST                 ; return from interrupt with shadow regs
Setpoint is handled as a LONG, but if you can use a BYTE sized result, you can change it to Setpoint.byte0 to reduce it by a few instructions.

The NO_CLRWDT drops a couple more instructions, but make sure the WDT is OFF.

Compiled, it looks like this, including both handlers ...
Code:
_ISR
        btfss   INTCON3, 001h
        goto    _RollOver
_DoStep
        btfss   PORTB, 001h
        goto    L00003
        incf    _Setpoint, F
        clrf    WREG
        addwfc  (_Setpoint) + 1, F
        addwfc  (_Setpoint) + 2, F
        addwfc  (_Setpoint) + 3, F
        goto    L00004
L00003
        decf    _Setpoint, F
        clrf    WREG
        subwfb  (_Setpoint) + 1, F
        subwfb  (_Setpoint) + 2, F
        subwfb  (_Setpoint) + 3, F
L00004
        bcf     INTCON3, 001h
_RollOver
        btfss   PIR3,  002h
        goto    L00005
        btfss   QEICON, 005h
        goto    L00007
        incf    _Position??WORD1, F
        movlw   0
        addwfc  (_Position??WORD1) + 1, F
        goto    L00008
L00007
        decf    _Position??WORD1, F
        movlw   0
        subwfb  (_Position??WORD1) + 1, F
L00008
        bcf     PIR3,   002h
L00005
    RETFIE FAST                 ; return from interrupt with shadow regs
Hope that gets it closer.