hex viewer / editor .. how to show all bytes at the same time ?

[l.impedance]

Hello everyone
i am a new developper and i am very interested to this great soft AMS 8 it's easy & powerful
i want to build a simple hex viewer & editor and show all bytes to grid object or input ( like this photo )



but the problem : the time of execution is too late when i open a file bigger then 20kb

any suggetion please
how to show all bytes at the same time in the grid object or input ...like the other hex editors ?

my source code

FilePath = Dialog.FileBrowse(true, "Locate File", _DesktopFolder, "All Files (*.*)|*.*|", "", "dat", false, false);
if FilePath[1] == "CANCEL" then
    Application.ExitScript();
end

-- Delete cells from the grid
Grid.SetRowCount("Grid1", 1);


local f = assert(io.open(FilePath[1], "rb"))
local block = 10


binTb = {} --//16
ii = 1;-- number of bytes = i*16
jj = 1;-- count 1 to 16 and return
binTb[ii] = {}; -- 16 case = 16 byte

while true do
    local bytes = f:read(block)

    if not bytes then
        break
    end
  
  for b in string.gfind(bytes, ".") do    
    
    if jj ==  17 then -- in the 17 ... 1 ( 0 in binaire ) ( 16 byte / binTb[ii] )
        ii = ii+1;
        jj = 1;
        binTb[ii] = {};
    end
    
    binTb[ii][jj] = string.format("%02X ", string.byte(b));
    jj = jj+1;
    
  end
end


-- Add to grid
for i,j in pairs(binTb) do
    result = Grid.InsertRow("Grid1", -1, false);
    for ii,jj in pairs(binTb[i]) do

        Grid.SetCellText("Grid1", i, ii, jj, true);
        Grid.SetCellColors("Grid1", i, ii, {Background=0,Text=16777215}, false);
    end
    Grid.SetCellText("Grid1", i, 0, Dec2Hex(i-1), true); -- start from 0
end

for i,j in pairs(binTb) do
    byte2char = "";
    for ii,jj in pairs(binTb[i]) do
        byte2char = byte2char..jj
    end
    Grid.SetCellColors("Grid1", i, 17, {Background=0,Text=16777215}, false);
    Grid.SetCellText("Grid1", i, 17, byte2char, true);
end
Grid.Refresh("Grid1");

the function

function Dec2Hex(nValue)
    if type(nValue) == "string" then
        nValue = String.ToNumber(nValue);
    end
    nHexVal = string.format("%X", nValue);  -- %X returns uppercase hex, %x gives lowercase letters
    sHexVal = nHexVal.."";
    return sHexVal;
end

[l.impedance]

No one can help me :(