Random Fps drop in minecraft?

Well. This was random. 1 day playing minecraft fine no lag next, horrible fps drop.

Well. I have a great computer. I have 16 gb of ram on it.
Anyways, this is only minecraft. I have fast internet and all of my other games run on high fps.
Also, i don't think i downloaded anything that could of slowed it down. I've tried turning all my settings down low but still bad fps.
If anyone could help that would be great.
I've already tried optifine and re-installing it so don't tell me to do either.

Maybe it was loading chunks because when it does that there's frame rate lag, but if it's still going on in not sure maybe it's your graphics card? You could try playing regular Minecraft on a launcher called technic launcher I hope this helps.

Decreasing the number of chunks loading might solve the problem by the way try using optifine