Better instanceof check (#21)

* Better check on whether setImmediate can be used

* Documentation on config.prioRequestsProcessing and setImmediate

Author: schamberg97

README.md

@@ -74,14 +74,18 @@ server.listen(3000)
   ```
 - **cacheSize**: Router matching LRU cache size. A given value <= 0 will disable the cache. Default value: `1000`
 - **errorHandler**: Global error handler function. Default value: 
+  
   ```js 
   (err, req, res) => {
     res.statusCode = 500
     res.end(err.message)
   }
   ```
 
+* **prioRequestsProcessing**: `true` to use SetImmediate to prioritize router lookup, `false` to disable. By default `true`, if used with native Node.js `http` and `https` servers. Set to `false`, if using Node.js Native Addon server, such as uWebSockets.js, as this will cause a huge performance penalty
+
 Example passing configuration options:
+
 ```js
 const sequential = require('0http/lib/router/sequential')
 const { router, server } = cero({
@@ -180,6 +184,7 @@ wrk -t8 -c40 -d5s http://127.0.0.1:3000/hi
   `Requests/sec:  82682.86`
 
 > For more accurate benchmarks please see:
+>
 > - https://github.com/the-benchmarker/web-frameworks
 
 ## Support / Donate 💚

index.js

@@ -1,14 +1,27 @@
 const http = require('http')
+const httpServer = http.Server
+const httpsServer = require('https').Server
 
 module.exports = (config = {}) => {
   const router = config.router || require('./lib/router/sequential')()
   const server = config.server || http.createServer()
 
-  server.on('request', (req, res) => {
-    server instanceof http.Server
-      ? setImmediate(() => router.lookup(req, res))
-      : router.lookup(req, res)
-  })
+  config.prioRequestsProcessing = config.prioRequestsProcessing || server instanceof httpServer || server instanceof httpsServer
+
+  /*
+  Native server can also be https server, so we also need to check for it.
+  Unfortunately, there appears to be no proper way to check for http2 server.
+  */
+
+  if (config.prioRequestsProcessing) {
+    server.on('request', (req, res) => {
+      setImmediate(() => router.lookup(req, res))
+    })
+  } else {
+    server.on('request', (req, res) => {
+      router.lookup(req, res)
+    })
+  }
 
   return {
     router,