Starting up Eb always takes long due to the number of files processed.

Since you do not specify the details of your installation, it would be just guesswork to answer.
Standard installation procedure would be :
Install Rome (on an OS with UAC (Win7, Vista) don't install to the "program files" folder; use eg. "C:\CA\Rome")
Install BI
install BI patch 1.6 (includes Rome 1.5), if your game has not already the version (eg. Rome Gold is already 1.5 and 1.6)
startup the game to see if it is working. Configure audio, video etc for your system.
copy the whole folder where you installed the game (where the rometw.exe is found) with all subfolders to a new folder (eg. "C:\CA\EB"); if anything goes wrong you then still have a working installation of vanilla Rome
install eb 1.1
install eb 1.2 patch
install ferromancer's mod (EB on BI" found here: https://forums.totalwar.org/vb/showt...arian-Invasion )
some people seem to have problems, when installing ferromancers mod before patch 1.2. Since the mod seems to contain the fixes of patch 1.2 you could skip the installation of Patch 1.2.