Hello Eugene,
Great job, it was a breakthrough!
My weights:
Had no difference in performance, or excessive queries to the database, even because you developed the widget based on cookies. For performance that’s good, now just clear your browser cache and empty widget.
My humilte opinion:
The advancement in which I refer would be to develop a way that all comparisons of users stay on saving custom post. So could for instance configure the WordPress SEO plugin, specific titles and descriptions for products compared, eg:
Title: Galaxy Galaxy S3 vs S5
Description: See a comparison between the Galaxy S5 vs the Galaxy S3, learn what are the main differences.
This would be saved in a custom post, so he would enter the sitemap WordPress SEO. Yes it would certainly result in a great SEO.
The site will have “content” generated automatically based on the comparison of users.
When a user make a comparison that does not yet exist in the custom post, he would save. If there is already comparing the user is requesting, simply redeem the custom post this comparison …
I know it’s more complex, but I believe within your level development is possible … that would be a machine to generate traffic …
Suffice for the administrator to insert the product, and wait for the comparisons of the users … like this:
https://www.morecellphone.com/