In the first part of a sync, there used to be some feedback about the progress of the file list download. The number of files received were shown below "receiving file list". As of portage 2.1-r1, this is no longer shown. This progress message can be very important to users on slow connections (especially dialup) as an indicator of the time remaining to sync completion.
Add PORTAGE_RSYNC_EXTRA_OPTS="--progress" to /etc/make.conf. Alternatively, add --verbose to the emerge --sync command line.