[common] Watch script is too heavy

[Hardtack]

We are using lerna for managing packages under @react-mdc.

When we try to use tsc --watch for each packages, they start processes separately for all packages.

So, at the beginning of watching, they take tons of resources, since all of them try to build their sources.

Is there any nice solution for integrating typescript with lerna? or should we have to make our own watch script?