What tells you that Avast is the last program to load ?
And what is the reported program file being reported ?
I suspect you are looking at the avast tray icon AvastUI.exe (not an integral part of the AV protection) and thinking that is the time the program is loaded. Avast loads low level drivers, etc. fairly early on in the boot.
I would certainly cull programs from loading on boot unless they are needed immediately, if Smart Audio is a media player, I would leave that to be loaded only when I launched a media file.