Running two scripts in parallel

I want to start running a side script from withing my main script. I want the side script to run in parallel to my main script, meaning I want my main script to keep on running commands after initiating the second script, disregarding entirely the fact that a second script is running.

I tried using the batch function: I put tic and toc before and after the code I wanted to run parallel (to measure it's time). I then replaced the code with batch(script) (script being said code). Using batch took longer than the normal way.

What am I doing wrong? How should I proceed?