Hi @Apurva,
For lazy-loading builder blocks, you can refer to our forum post at Lazy loading Builder components
We recently released Partytown in beta, a lazy-loaded library that helps relocate resource-intensive scripts into a web worker, and off of the main thread. Its goal is to help speed up sites by dedicating the main thread to your code and offloading third-party scripts to a web worker.
Introducing Partytown 
: Run Third-Party Scripts From a Web Worker & How partytown works