After reading this very interesting link through wpmudev on reducing images for your website to improve page load, I decided to install Caesium software and give it a try.
I successfully reduced the size of my images by a staggering 85% + after setting the quality output at 50%.
Since I do use a lot of product images on my site, I felt that it would greatly improve my seo possibilities by compressing the overall size of these image files. (over 400 images in just two months I think!)
Although my website is only a few months old I had two monthly image files to compress and I was able to do this very easily, following Joe Foley's instructions using cPanel.
Unfortunately, only the first month worked properly and the second month would not show up in their respective featured image links etc.
I did try this procedure twice and got the same results but can't work out why the second months file would not work. I did have one mp3 within the second file and I removed this from the file before compressing it, as advised, and then I inserted it back again after compression of the image file.
I am wondering if in some way the structure could have been altered, resulting in the results for file # 2 mentioned above!
If anyone has any experience with this type of issue or can provide a possible solution to the above then it I would be much appreciated.