Rsync backup

How do i use Rsync yo pickup only new or modified files from source?
I am using rsync -ravzpotu --delete-excluded but sometimes it goes thru all files again

It has to go through all flat file inodes to find time modified. Unlike MULTICS, UNIX ufs does not have a modify time that rippples up through the tree, so you have to check all periodically. No free lunch.

Is it doing more?

it always recivies an incremental lis containig old files that has not been modified.

It logs a list of OK files?

the list i recive it the incremental list. so it downloads the files again

Is there a difference in the systems that might make times look different, like unix-windows? Try -c.