Here are some tools to help you keep an eye on page speed and page speed scores:
Google PageSpeed Insights
Click here to use this tool.
Click here to use this tool. Make sure to change the region of the test to suit the region(s) your site will be working in.
Experte - Page Speed test
Click here to use this tool. This tool allows you to test hundreds of URLs automatically. All you have to do is enter a URL, and the tool crawls the website and determines the page speed scores for each subpage. Experte say the data yielded is identical to the data of Google PageSpeed Insights.
Page load time Chrome Plugin
Click here to visit the install page.
Image Optimisation Tool
Compressnow is great for retaining good quality while reducing the overall file size significantly.
Click here to view their website.