What are you running on your G1?
I used one until last week and was never "extremely" slow although it did sometimes take a second or 4 if you were switching around big apps with lots of stuff running in the background. Like say you have Sport-Tracker running and you switch between that, Chrome, Whatsapp, Facebook and your banking app.
Doing the same on the G3 is a lot faster, even with the same 1GB of RAM. The reason for that is the Quad-core 1.4 GHz Cortex-A53 CPU is faster at reloading apps that were tomb stoned. The old Quad-core 1.2 GHz Cortex-A7 in the G1 was pretty snappy on Kitkat which is my point with regards to getting a 2GB G3.