I have no idea how this happend i will now just say what i did and what happened.

1. I put this command
/summon AreaEffectCloud ~ ~1.2 ~

{Particle:"cloud",Radius:300,RadiusPerTick:-0.4,Duration:1200}

in a impulse command block
2. i run this command block
3. it created lags
4. the lags stopped after 5 seconds
5. i moved a lot of blocks back to watch it from further away
6. i saw a giant fire getting smaller and smaller

Sorry for this BAD explanation xD