If, through Toast, you plan to re-encode the .avi as a DVD (Video tab), Toast is well known to be so slow.
And depending on the codec used to create the .avi file, Toast can be slower... yes, it is possbile
In my case, a typical 20' minutes when I drag a 700MB .avi file to the Toast803's Video window before gaining the focus again ... is ?normal?
Such a long time was not with Toast 7.0 !
So, tired of this latency time, I decided to buy a home dvd-player which can handle avi/divx file: less than 50$
Opening a Data/DVD-ROM(UDF) Toast's window, I burn 4 or 5 .avi files on the same DVD without the need to re-encode them