Android studio takes more memory as well as internet because Android studio is capable of handling all the dependencies automatically (using gradle just like maven in java EE). All tools that does debugging on the real time occupied memory and process cycles. Also the emulator UI quality improved in Android Studio emulator in comparison to Eclipse. So threads and processes takes up huge amount of memory space.
If you still want to lessen the memory issue follow this link hope that will help you
solved android studio on a machine with less than 2GB RAM