PIC BASIC TLC5940 code

[wolwil]

How can I get this to stop flickering? It flickers even at 16MHz. With 4 MHz it taks the GSCLK about 250 ms to complete making all the GSDATA that are 0's really stand out causing a flicker.

Is there some other way I could do the GSCLK so I am not just turning the GSCLK pin H/L 4096 times?

ANSEL = 0 'ALL DIGITAL
CMCON = 7 'COMPARATORS OFF
TRISA = %00000000
TRISB = %00000000

DPIN        CON     7
SCLK        CON     6
XLAT        CON     5
BLANK       CON     2
VPRG        var     PORTA.0
DCPRG       var     PORTA.2


C1          var     byte
C2          var     byte
C3          var     word

GSDATA      var     word

GOSUB preset
'***************************************************
'*                    Main Loop                    *
'***************************************************
LOOP:
FOR GSDATA = 4095 TO 0 STEP -16
    gosub setgs
    gosub lightemup
NEXT
FOR GSDATA = 4095 TO 0 STEP 16
    gosub setgs
    gosub lightemup
NEXT
goto LOOP
'***************************************************
'*                      Set GS                     *
'***************************************************
SETGS:
for C1 = 0 to 15                        ' for 16 outputs
    shiftout dpin,sclk,1,[GSDATA\12]    ' shift out 12 bit GS Data
next
    PORTB = %00100000                   ' high xlat
    PORTB = %00000000                   ' low xlat
return
'***************************************************
'*                   LIGHT EM UP                   *
'***************************************************
LIGHTEMUP:
PORTB = %00000100                       ' high blank
PORTB = %00000000                       ' All outputs = ON 
for C3 = 0 to 4095                      ' Generate 4096 GSCLK pulses 
    PORTA = %00001000                   ' GSCLK HIGH 
    PORTA = %00000000                   ' GSCLK LOW 
next
return
'***************************************************
'*                      Preset                     *
'***************************************************
PRESET:
'HIGH DCPRG
HIGH VPRG                               ' Put into dot correction mode
HIGH blank                              ' All outputs OFF
low dpin                                ' Starts dot correction
low xlat
For C1 = 0 to 15                        ' 16 Ports
    shiftout dpin,sclk,1,[%111111\6]    ' 6 bits of Dot Correction per port
next
high xlat                               ' Latch bits into dot correct register
low xlat
low VPRG                                ' Enter GS Mode
for C1 = 0 to 15
    for C2 = 0 to 11
        shiftout dpin,sclk,1,[%111111111111\12] 
    next
next
high xlat                               ' Latch bits into GS register 
low xlat
high SCLK                               '193rd CLK pulse
LOW SCLK
low blank                               ' All outputs = ON 
return

NOTE: This code is basically the same as the above Adruno code but I have a different fade routine. The above code used direct PORT addressing for GSCLK like I did but they were using an 8MHz Adruno for their project and it worked fine. I don't understand why this will not work in PBP with 16 MHz running the show.