docs: Add CUBEJS_TRANSPILATION_WORKER_THREADS

Author: igorlukanin

docs/pages/reference/configuration/environment-variables.mdx

@@ -1293,6 +1293,21 @@ learn more.
 | --------------- | ---------------------- | --------------------- |
 | A valid number  | 86400                  | 86400                 |
 
+## `CUBEJS_TRANSPILATION_WORKER_THREADS`
+
+If `true`, optimizes data model compilation by running critical parts of the
+code in worker threads.
+
+| Possible Values | Default in Development | Default in Production |
+| --------------- | ---------------------- | --------------------- |
+| `true`, `false` | `false`                | `false`               |
+
+<ReferenceBox>
+
+See [this issue](https://github.com/cube-js/cube/issues/9285) for details.
+
+</ReferenceBox>
+
 ## `CUBEJS_WEB_SOCKETS`
 
 If `true`, then use WebSocket for data fetching.