I use Gemini Apps Manager. I think it does the same thing as autostarts (haven't tried autostarts). Requires root. Very easy and useful program.
It can certainly help the performance of your phone (battery and memory/speed) to block these type programs from auto-starting. Many of the programs that auto-load on start (for example Google Maps) have an associated service... which makes them high priority... they won't unload easily. Android will flush your other programs (maybe some you want to use) before it flushes the service.
I blocked Google Maps so it doesn't start on boot. The program is still available to me, it just doesn't start until I want it to.