Open Framerate suddenly drops to around 5ps, only restarting the client helps



Summary of the problem Framerate suddenly drops to around 5ps, only restarting the client helps

Pack Version 2.6.0

What is the bug? I usually get around 40fps, but without warning my framerate drops to around 5fps. Logging off the world does not help, as I see that the mouseover highlights on the main screen (where you select single or multiplayer etc.) are extremely laggy. Only quitting the client and restarting helps.

I think alt-tabbing out of the client to eg. check something in the browser can trigger this, but it definitely happens without that, too. I'm playing on a server, but the other people on there do not experience this problem.

When this happens I can see in the debug overlay that the memory allocation is relatively stable. It can stay around eg. 60%.

This happens with both Curse and FTB launchers with default settings. I'm using the Sphax texture pack and run Windows 10.

Any ideas what might cause it? How to debug or fix?

Mod & Version Infinity Evolved 2.6.0

Link to log file

Is it repeatable? I don't know how to trigger it, but it happens on pretty much every play session at least once. Today it happened less than one minute from logon.

Known Fix


Okay, after some experimentation I was able to find out more!

It seems that the Sphax patch for Infinity Evolved is the culprit, and that the problem has to do with animals, at least cows.

If I have the patch enabled my framerate drops to around 5fps if there are cows in my field of view. If I turn so that the cows are not in my field of view (even far away) or if I kill the cow(s) the framerate immediately jumps back to 40+. Interesting that the actual Sphax pack itself does not exhibit the problem, only the patch.

So the workaround for me is not to use the patch. This is unoptimal, because it makes most non-vanilla stuff look horrible compared to the otherwise nicely textured world. I need to try other versions of the patch.

Anyway, this bug report can be closed as it doesn't seem to be related to the modpack itself.


Well-Known Member
Feb 2, 2013
What texture pack resolution are you using and how much ram have you allcated to Minecraft? using a lover resolution texture pack or slightly increasing ram might help.