perf!: reduce default brotli compression factor to 4, was before 11 (…

…maximum) (#278)

* perf(index): reduce default brotli compression factor to 4

* docs(readme): change default value of brotli quality

README.md

@@ -169,7 +169,7 @@ You can tune compression by setting the `brotliOptions` and `zlibOptions` proper
     brotliOptions: {
       params: {
         [zlib.constants.BROTLI_PARAM_MODE]: zlib.constants.BROTLI_MODE_TEXT, // useful for APIs that primarily return text
-        [zlib.constants.BROTLI_PARAM_QUALITY]: 4, // default is 11, max is 11, min is 0
+        [zlib.constants.BROTLI_PARAM_QUALITY]: 4, // default is 4, max is 11, min is 0
       },
     },
     zlibOptions: {

index.js

@@ -117,7 +117,12 @@ function processCompressParams (opts) {
   }
 
   const params = {
-    global: (typeof opts.global === 'boolean') ? opts.global : true
+    global: (typeof opts.global === 'boolean') ? opts.global : true,
+    /**
+     * Default of 4 as 11 has a heavy impact on performance.
+     * @see {@link https://blog.cloudflare.com/this-is-brotli-from-origin#testing}
+     */
+    brotliOptions: { [zlib.constants.BROTLI_PARAM_QUALITY]: 4, ...opts.brotliOptions }
   }
 
   params.removeContentLengthHeader = typeof opts.removeContentLengthHeader === 'boolean' ? opts.removeContentLengthHeader : true