After several hours/days of running against a 60 GB drive (G4 used as a FireWire 400 target drive - 30 GB free space) the app slows down to a crawl and complains with a pop-up message:
"Disk Full Alert!!", "Warning: Your hard disk has no more space available for application memory. Further application disk activity may have been suspended.", "To free up some memory, select application's name and click Force Quit."
I've opted to simply close the window as the app continues anyway and the ONLY other app is the Finder. Eventually it almost stops working entirely - always before finishing Volume Optimization (current task).
I managed to eventually run Activity Monitor and found that on the host mac (running TT Pro) the free space suddenly jumped from 800 MB to 1.2 GB after I just quit (normally) TT Pro. This suggests a memory leak with your app where its internal memory 'housekeeping' is faulty as it accumulates and doesn't dynamically release memory appropriately.
Once I restarted TT Pro's Volume Optimization where it left off it immediately ran swiftly to completion (at that point it didn't have much to do anyway).

Why do you NOT fix this obvious memory leak? Users have been complaining about how slow TT Pro is for a VERY LONG TIME!!! We CANNOT afford to use TT Pro on clients/businesses - its too expense to run - because it takes to unreasonably long to run - due to bad programming!

Please QC your product better and submit an update as soon as you can!!!! Thanks!