That's your problem. I was burned by the same thing when I built my first "big-long-running" script. If there is one rule I can summarize...you have to REUSE all widgets in Tk, or there will be leaks. Somewhere deep down in the innards of Tk, references to all objects are kept, and not released until the end of the program. I know it is a pain to deal with, but once you learn the tricks, it isn't too bad.

For instance, you say you open a fair number of windows, then destroy them....that is memory use going up. What you want to do, is pre-create a set of reusable top-level windows, each packed with the widgets they need (which will also be reused), and "withdraw" them. Now, when you need to load them with data, loop through them all, and "configure" each of them with the new data, then "raise" the toplevel. When you are done, don't destroy the toplevel, just "withdraw" it. When you need the next toplevel, just loop through the withdrawn toplevel(and it's widgets) and "reconfigure" them with the new data, then "raise" them again.

I have made some big programs run this way, loading, unloading, and reloading data, without memory leaks. The memory will increase to the size of the largest "instance" of the toplevel, but will be reused, and generally will level out at some average value.

Photo objects can be "emptied" with $photo->blank, text widgets can be blanked with $text->delete('1.0', 'end'); etc, etc.

I've found almost all widgets can be reused, without leaking, with the exception of the Progressbar.

Most Tk apps are small, and tend to do something then exit; so the small memory gains, created by using "destroy", can be ignored. But long running scripts have to be caarefully planned.