Hey /kksou, thanks for your ongoing assistance, hopefully after a few weeks I'll be able to answer a few questions for you, give you a bit of time off :D
Anyway, I can see that the cell_data_func call in itself is not a performance hit. Whilst writing my reply and pasting my code to this post, I noticed that I had a call to another class that returned the status of each individual entry and it was this accessing of the outside class that was making the application jerky and unresponsive.
Back to work! Speak to you soon no doubt :)
Regards, Paul.