> but if you have a large file. wouldn't it just need
> to vefify the total number of bytes downloaded ? It
It queries the server (file size and modification date) and only redownloads
files that have changed. Dynamic html files are created on the fly and always
redownloaded. Queries are usually 3-5 files/sec (limited by round trip
times.)

> looks like its actually going though bit by bit
> compare... 
No idea what your seeing.