Unity 5 and iPad don't play together very well?!

I have been making a game with Unity 4.6, then upgraded to 5 after it was officially released.
My game ran very well on both iPhone 5 and iPad 3rd Gen.
However after the upgrade, iPad framerate dropped to 13 / sec!!!
While iPhone is strong at 30 and could go up to 60 too.

I have disabled the GI by selecting Back GI and Precomputed Realtime GI.
Also, no Shadows.
I have 10k Tris and 30 Calls average, calls might go up to 45, then get patched due to an atlas, so mostly around 30 to 35 calls.
Now i know for sure that this should work with no flaws at 30 /sec on iPad 3rd gen. But for some reason, it's not!!

Is there a known issue with the new standard shader (physical shader) and iPads ?

 

very helpful community , wow !

Alright after digging into the problem, i found that removing the back wall which covered the whole level, which sets in a sic-fi environment did the trick. However i am unable to know why !!!!

The wall is just a normal plane model with standard shader and a 256k texture!
No matter what i did, removed the wall, added different model, added bunch of different ones, different texture, resize the texture. No matter what i did, iPad will not accept the back wall!!!

It sounds crazy and i think it is crazy, it must be a glitch in Unity 5 , if i add other models, which has more vertices or higher texture , the game still runs fine, but adding any walls , no matter what , just breaks everything and frame rate goes to around 12 / sec . remove the wall , and it's back to 30!!

I have made so far about 5 test scenes , each with different back walls, different textures and models. None is accepted by the iPad!!!
Even though iPhone 5 is solid 60/sec , iPhone 4 is solid 30 / sec.

Go figure.
I hope a Unity expert can shed a light on this!

 

i have also a ground that spreads through out the scene and a ceiling , removing them , has no effect whatsoever , so if i remove the ground and the ceiling which are basically the same as the back wall , but with more vertix , and leave the back wall only , still 12 / sec framerate ! remove the back wall , everything is fine , and i get 30 / sec and more if i want to run at 60 / sec ,, so the only difference that i can think of is that the wall is facing the camera , while the ceiling and the ground are not!!!

What is going on with Unity 5 !!!

 

I have another issue with unity 5 using skinned mesh render. I hope that gets fixed rather soon :-(
at the moment it is not ready for production

 

I have a similar bizarre problem.

I have an extremely simple test scene (2 or 3 cubes and planes, that's all).

It plain will not run on iPad Mini, with iOS8. So - the objects simply do not appear at all, they are invisible, the shaders do not work. I tried every shader (standard, diffuse, mobile, legacy diffuse).

It runs OK on a brand-new iPad with iOS9, but bizarrely just won't run on an iPad mini, iOS8.

What a shame.