Zombie pigmen are VERY difficult to kill especially if playing on hard difficulty. Since all of them wield golden swords, they do additional damage, doing about 5 hearts on hard. With full iron armor, the player will be killed in about 3-4 hits from a normal zombie pigman.

To add to this, they are very laggy and their hitboxes for striking the player are bigger than many other mobs. This can actually cause them to be able to hit the player when the player cannot reach them with their weapon, such as around corners.

This is not an FPS or multiplayer connection issue as I tested it on singleplayer with an average of about 90 FPS in normal survival mode.

This has been overlooked for many updates, but I think that it's a real problem that needs to be addressed.