Excel Extremely slow when zooming to 10%

Riny_van_Eekelen 

Hi Riny:  I appreciate the guidance.  I have now created a simple version of my spreadsheet and I called it Exceltest.  The sheet is comprised of data 640 columns x 400 rows (top 1/2 of sheet) that was converted from a RAW file originally in hex from a camera.  The lower portion, I created a conditional formatting to convert that to a gray scale and where I can see the image I am working with.  My challenges occur at the 10% zoom level.  When I copy a block of the top data for example and paste it to another location (just as a test) - say 100x100 cells - Excel bogs down on a number of computers and virtually halts.  On some others it works flawlessly.  Normally I copy the entire 640x400 rows from another excel sheet over the existing one as I keep processing and working with the image.   My old computer (Inspiron 5555 AMD A10-8700P Radeon R6, 10 Compute Cores 4C+6G, 1800 Mhz, 2 Core(s), 4 Logical Processor(s)) it works but slowly.  On my more powerful Intel with NVDIA it bogs down and I am forced to shut down Excel as it does not respond.  Task manager shows lots of CPU, Memory and Graphic resources (all below 40%) when I run Excel on both computers.   There must be something unique about Excel and the computer that bogs down this spreadsheet that I would appreciate a solution or suggestion.  I enclose the spreadsheet.