Hi Philippe:
Sounds like you need to use a router then.
30 seconds is a long time for the page to load anyway, do you know why it takes so long?
Anyway here is another idea which should work.
Instead of redirecting to the mobile page after the desktop page has loaded create a proxyHome page.
This page is blank (don’t add any content because it redirects immediately so will load very quickly.
It’s page code is very simple you just need to make the proxy page your home page in the page settings and then add the code shown in the diagram below.
Perhaps this will do the trick.
Steve