Hello,
Thank you for reaching out to us with your query.
Regarding your question about the image size in terms of data volume, the optimal size can vary depending on several factors, but generally, we recommend keeping the image file size under 200 KB to ensure that the page loads efficiently while maintaining a good quality.
There are different ways on how to compress images. Use special services or WordPress plugins to optimize your images for decreased loading times: tinypng.com, Compressor.io, Kraken.io, EWWW Image Optimizer, Smush Image Compression and Optimization plugin.
As for the issue you mentioned about the image wobbling or quoting when scrolling, please record a video and provide the URL here.
Best Regards,
8Theme’s Team