Falang slows down the loading of the backend

-- HikaShop version -- : hikashop business v2.4.0 2015-04-20
-- Joomla version -- : 3.4

Hi,

after upgrading to Joomla 3.4 I'm having lot of problems in translating Hikashop.
I have installed Falang latest version (because is the only option) and soon after I have noticed some slowness to load pages in the admin backend.
Unfortunately I couldn't use Falang to translate the rest of the site because is not working properly (doesn't translate menus) and they don't give support for the free version. So I had to use the Joomla native system.
But it seems that the two are totally not compatible and the result is an incredible slowness!
More then 1 minute for loading pages (not all pages but most and especially HikaShop) and it is really impossible to work.
So I've decided to move the site to a different domain (it was even better for me) and I started to set it up again, a brand new installation, but I'm having the same problems.
It is Impossible to use Falang because still do not translate menus (it means all the rest of the site) and is not compatible with Joomla multi language site.
So or I use one or the other... or I translate the site or the shop.

I am stuck, I really need your help...