Hello,
Actually, Size of the Images is controlled by WooCoomerce and it works like described below:
The core functionality of WooCommerce is that it is only able to change the size of an image from Large to Small, not from Small to Large.
Let’s take an example:
Like you have 2 products on your site both have different image dimensions.
1 has 400*400
2 has 200*200
Now you want to change the size of the images as 300 right.
You can change it easily from WooCommerce >> Setting >> Customize >> WooCommerce >> Product Catalog.
But when you set the size from there as 300, the 1st product image size will be successfully changed because it will change the size from Large to Small but the 2nd product image size will not change because it is already small then 300 and as I told you already that WooCommerce by default has not provided the functionality to change the size from Small to Large that is the original reason the images look blurry.
So you have to set the Image Size again as it was before, and for site Speed Improvement, Use any plugin which will Compress your Images not Resize it.
Hope this is all clear and understandable now.
Best Regards.
.
