To improve startup time go to the Strings directory inside the Van Helsing install directory. Delete every directory except the language you use. Like here:
For improving genereal game performance go to the Van Helsing install directory and look for a specific .exe for your operating system, 32 bit(x86) or 64 bit(x64) architecture and DirectX version you want to use. In my case i am using Windows 7 64 bit and DirectX11 so i will choose VanHelsing_x64_11.exe. Start the game using that .exe.