We use WPMUDEV and Hummingbird but this and Google Insights is showing some points that show the site is slow but we need your help in optimising things.
4 of your cache types don’t meet the recommended expiry period of 8+ days. Configure browser caching
But the details lower on the page say Automatic browser caching is active.
How do we fix this?
Remove unused CSS – 75/100
You can save 213 KB by defering the following CSS files.
Most of these appear to be wpmudev css files, for example:
Can these be deferred?
Serve static assets with an efficient cache policy
Browsers download and cache (store) assets locally so that subsequent visits to your pages load much faster. You have the ability to specify how long cached assets are stored before the browser downloads a newer version. Ensuring your resources have reasonable expiry times will lead to faster page loads for repeat visitors.