There is some process to make it faster just like when you use coins.ph app. If 2 user are using same coins.ph and transfer BTC to each other. There will be no transaction applied and the transfer is instant. I think is using some kind of self miner to process all the transaction happened on their own wallet address.
yes that's right 'cause coins.ph (wallet) is now accepting 3 different types of currecy which is "php,btc,eth" and you can send to anyone whithout transaction applied after.. It's so fast and reliable to use , no hassle within a second or minute you will receive it instant.