Weird flickering on barrels, machines and other things?

[Kalagorn]

So I've been having this weird flickering, which is hard to describe, on barrels and machines. I'll just post some screens to illustrate:

I'm using Sphax and Optifine on Infinity. Anyone know the cause?

 

[jordsta95]

Probably Optifine.

Optifine has had a lot of issues with Forge for a while now.
Although it works, it isn't as "plug-and-play" as it used to be.

This isn't stated on the fact that it is, but it probably is, knowing what I have seen with other complaints/issues with it

 

[ScottulusMaximus]

It's Optifine, turn fast render off under "performance"

 

[Kalagorn]

It's Optifine, turn fast render off under "performance"

Thanks a lot, that fixed it.