I love Google developers' tool for improving the speed of my site - https://developers.google.com/speed/pagespeed/insights/ It not only gives suggestions about the Desktop version of your site, but also the mobile loading time! Which in my opinion is great as it is 21st century everybody MUST HAVE a responsive site! :-) Cheers
hi, I am using - https://www.webpagetest.org/ - I think it is the oldest speed measuring tool online. It is free and if you really want to dig into flash-loading web-site I would suggest to use it! It gives a lot of suggestions!
Oh, also - it can make a video (which you can even download it!) about the loading time of your site :-) After you make all the improvements you can compare the speed :-) Niiiice!!!
I like these 2 online services which are free and will help you a lot with the suggestions given! The sites are:https://tools.pingdom.com/
and my favorite:https://gtmetrix.com/
I love GT Metrix because you can easily improve your images without going to additional services for compressing images.
Simply go to https://gtmetrix.com/ and under "Optimize Images" you will be able to download the compressed ones and upload them by using FTP :-) Love it!
The suggestions given above are also useful and you can use them all! :-) Hope I've helped you a bit...