I also had a map. It was a empty world(floating temple map). I hearded random explosions( there wasn't lightning) and also the mobs acted "weird" So you're not the only one had a weird map
At my first world, i had 1 fps per 30 minutes When i saw that there were monsters in the night i made a 1x1 tower and waited untill the day Then i maded a cave house. One time there was flying green thing falling from the sky and it hitted me. I was frightened to death Now i'm playing minecraft for 4/5 years