Web worker usage

[Revln9]

Hi , i have a problem with recordings that are more than 1 min long , it takes a lot of time to compress in MP3 and on top of that , it blocks the thread (window freeze). i think the usage of web workers for this kind of job will be more suitable.
But i'm not really sure what blocks the thread, because before compression there's a "filereader" call with big chunks of data getting in, needs to investigate more, in the meantime if someone has a workaround for this, it will be a good help, Thanks