We use Wordfence on all of our clients' Wordpress websites. It's an excellent, free security plugin and will protect your site from many possible attacks. You can download it from the Wordpress website here.
However, if you run with the default settings, Wordfence can slow down your website loading time considerably.
When we benchmarked one of our websites on the Pingdom Website Speed Test, we noticed that the Wordfence Live Traffic Logging was taking a huge 3.75 seconds to complete (see screenshot below). This was causing the page to take over 5 seconds in total to load completely - which is far from ideal!
The Live Traffic log can be safely turned off via the Wordfence options screen. The Live Traffic log is used to monitor every single visitor to the website including IP address, country location, page currently being viewed, referring page, etc, etc - in real time. Understandably this causes a slow down on page load time. Unless you need to monitor your website traffic in real time then we would recommend disabling this functionality (you can always turn it back on if you suspect some suspicious activiy and want to monitor the site's visitors for a while).
By turning off Live Traffic in Wordfence this process is completely removed from the page load and therefore 3.75 seconds is saved. Subsequently we are now achieving more acceptable results!...(this is an ecommerce website with multi-lingual translation)