Open 1.1.0: Skeleton Spawner Causes Massive Lag in Nether

[Drawman]

Version:
1.1.0

What is the bug:
When i put a normal skeleton spawner - which i obtained in overwold - in nether the game just goes crazy, it lags so much it took me 2 minutes to take the spawner i put 2 blocks away from me.
It happened before,
I removed the spawner, it fixed nothing.
I removed the file " DIM1 " from minecraft folder because i saw someone metioning that was the file which contains nether in it and if i delete it it will make minecraft regenarate nether.
It didn't regenerated the nether but after i restarted my computer i was able to get in the nether and wander around without lag.
The file " DIM1 " is still at my desktop.
I wrote those just in case.

Here is the log's part which is about the problem.
( i wanted the give you the full log but it was too big for pastebin.)
http://pastebin.com/raw.php?i=NLHHxa5R

I am using Soartex Fanver, And GenIndustry mod is deactived.

I am not a native speaker so i am sorry if i made any grammar/spelling mistakes.

Mod & Version:


Paste.feed-the-beast.com log:


Can it be repeated:


Known Fix:

 

[Fearlessagent]

I don't have any theories on the lag you experienced other than occasionally I'll have to relog because suddenly for no reason my FPS drops to around 2FPS when normally I get >120FPS.

However folder structure is as follows:

DIM1   -    End
DIM-1  -   Nether
region -   Overworld

 

[Drawman]

Thanks for the Folder Names
But i still need Wither Skeletons.
Anyone can help me ?

 

[Axis113]

I believe it's a bug with EnderIO separating wither skeletons from normal ones. It should be fixed by 1.2.1. If you don't want to update your version go to the EnderIO config and change the "replacewitherskeletons" option, it should be close to the bottom.

 

[Drawman]

Thank you so much @Axis113.
I know it could be the noobest question ever but, how can i update my version to 1.2.1 ?

Edit :
Oh, Nevermind i found out how to update my version.
( There is a little menu like thing saying " Recommended " i changed it to 1.2.1 )

Edit #2 :
Upgrading my game caused more lag for me ( Cheap Computer ), so i downgraded my game to its old version. It caused some problems with Steve's Factory Manager but it is fixed now.