Minecraft lags really bad but only started lagging after using the Woodland Mansion Explorer Map in survival mode. All settings are on default and I don't know what to do.

So I started a new survival mode and everything was fine. No lagging and settings were on default mode until I recently got a Woodland Explorer Map. As I was traveling to the place, it was starting to lag really bad and on the way back it was worse. This has never happened to me and I would like some answers to why it's happening.