I tried Bitpay (it uses something like Microsoft Access to store data), i'ts VERY slow, like 20 seconds to show one address (even on bitpay official website).

I think any database-free will be very slow. I'll give BlockCypher a try.


Edit: Just installed BlockCypher and discovered it is a front-end only source, it doesn't store anything, just make the api calls to blockypher database...