I want to make my api’s to run faster:

What I Do
i have been writing api’s and in that i get the data from parquet files directly,
i found that my api is loading slow on 50GB data and for that i have created a rollup concept which runs every 15min and get data from parquet files and store it in to sqlitedb and my api’s get data from sqlite db which make it faster but little bit and data which i am giving is also not live data.

can anyone help me on that or tell me which concept i should use

I am using express js as my backend