Apart from what others have mentioned.

If you are using NodeJS, it is optimized for I/O and not computation. Since it's single threaded and async at it's core, any blocking computation will impact entire service.

One approach could be to profile your app using a myriad of node js profiling libraries. (https://nodejs.org/en/docs/guides/simple-profiling/)

If you want a solution, try deploying your JS code as AWS Lambda or GCP Cloud Functions. They may address the issue at lower cost while you fix the issue.