Thanks for the reply. Yes I have thought of this but I couldn't find any blockchain explorer for Bitcoin Core... How would I create one by myself? Copy the whole blockchain to a database and how would I update/modify it with each transaction/change in the blockchain

Thanks for the reply. So how could I calculate the balance out of a wallet.dat file without having to search the addresses in a blockchain. I'm not trying to rely on a public API and the bitcoin core doesn't have a blockchain "explorer" as far as I know. So would I have to create a blockchain explorer first by storing the whole blockchain to a database? Are there any public projects that could give me an idea how its meant to be done...

Hello, I am creating an API that will connect to Bitcoin Core running on a server. The API would manage multiple wallets for a lot of users (up to 1000s)... Now I'm wondering how could I implement this to work as fast as possible. Is it possible to for example "getbalance" ("http://USER:PASS@localhost:8332/wallet/WALLETNAME") of a specific wallet without having it loaded? Because each loaded wallet takes about 10MB in memory.. And having 1000s of them loaded at the same time would take up a lot of ram and I am not sure how much stress it causes on the CPU for example, if anyone has any knowledge about this. Would it make sense for each API call to first load the wallet, execute the command and then unload the wallet? That would probably affect the performance. Any help is appreciated.