I am pretty sure that Bitcoin Core will automatically block bad peers, but you can still go to Help->Debug window->Peers and click on various peers to see more info or right click on them to show you more options, like disconnecting from them or blocking them.
Syncing should be an automatic process where you can just leave your PC running. Perhaps you are having some network connection issues.
Check your Internet connection and your firewall if you are using Windows (you shouldn't).
I've been disconnecting peers with a ping rate in 5 figures, but I'm not sure that these peers are my problem.
When I look at the histogram in Debug>Network I've got long gaps with no activity. This started with the last forced upgade of Windows ( which I didn't want). It's pushed me into re-activating my old Ubuntu node, and I'll switch over to that.