Past couple of days I've been getting 0 FPS (down from usual 40 ish) when moving about 25-30 blocks away in one particular direction from where my iron tank is situated. It's a big tank, 7x7x6 externally and was half full to full with lava for most of that time. It emptied out overnight and today when logging in I've noticed that I'm back to my usual 40 FPS. Coincidence? Are the tanks known for causing such issues and has anyone else experienced this?