NBT Data

The Named Binary Tag (NBT) format is used by Minecraft for the various files in which it saves data. The format is designed to store data in a tree structure made up of various tags. All tags have an ID and a name. from Minecraft Wiki

The way we access NBT through commands is more similar to JSON format, and isn't very complex.

Optimization

Unfortunately, any command directly connected to NBT Data, such as data, @...[nbt={}], execute if data, etc. Are creating big latency issues when used. It creates lags, freezes, unsyncs, unexpected entity jittering and more.

This is the reason why it is always a better practice to use interfaces - commands, that don't directly change NBT data. You can read more about them on Structure & Commands page.