i have tried Electrum but the protocol methods is limited. i want to make notification when there have receive transaction on my child address. if i am using Electrum or third party API, i must get transaction in every block and compare there is such address in my database, that's could have more resource if block have more than 1000+ tx.
That's not really a problem imo. Electrum is quite fast, which is the point of an SPV client.
There is also an alternative for e-mail notifications that are available on a platform such as
https://www.blockonomics.co/. You need to pay though.