Responsive Issue, header issue and landing page issue

Hey

I am using your fortuna theme to build up a new homepage for our small company.
I got along quite good but now I am facing some issues I cannot eliminate on my own.

My URL is: http://web50.server57.webgo24.de/bau-cooperation.com

Basically I am facing the following 3 problems:

1. My landing page is loading quite slow (sometimes up to 5 seconds even on new devices using fast internet (Germany / 50Mbit Connection)
Other website can be obtained normal and fast.
Google PageSpeed Insight shows something about blocking Javascript but whatever I tried after googleing the issue, nothing seemed to work.
I was not able to find a proper solution.

2. I decided to use Portfolio pages to show our projects instead of normal pages, because portfolios seem to be easier to handle and to aling.
So today I am recreating the projects as portfolio pages.
So my problem is: WHen I click “Projekte” (projects) and then I choose 1 of them the active header color of projekte is not blue anymore.
It seems the portfolio pages are not children of the Projekte page.

Also I would like to change one thing in the filter of the grid. It shows all cities where our projects took place and in the beginning it says “All”.
I would like to change “All” into “Alle” as we are a german small cap.
English words are just not fitting in when watching the frontend.

3. I am currently working on optimizing the pages for tablets and phones.
I already finished optimizing the Kontakte (contact page) but whenever I
rotate my tablet or phone from vertical to landscape or the other way round
I white bar and some distortion of the alignment are visible.
WHen I reload the page the issue is gone and everything is normal.
I would like to achieve that without reloading.
It should be possible to rotate the device and directly get a correct alignment and background.
I made some pictures for you to make it easier understand:

after rotating from landscape to vertical:

http://www.pic-upload.de/view-29567420/falsch.jpg.html

when reloading one time:

http://www.pic-upload.de/view-29567423/korrekt.jpg.html

I really have no idea what to try to get rid of thoses issues.
I would be nice if you could take a look at it.
Maybe you can easily fix it for me as I am really not that into that stuff.
I already created a login for you so you can access the back-end.
Where can I send you the löogin so nobody else can see it?

Thanks in advance