All I see now it is was deleted "for reasons of moderation".
How can I see what were particularly those "reasons of moderation"?
I've read faq about why would a question be deleted, but I can't find an explanation for my question.
Regardless of why it was deleted, your question had multiple problems even after it was edited.
First of all, you're asking multiple questions in one post ("What is the most significant item…" and "what is the best way to future-proof", how you can render your images as fast as possible).
Second, those questions are too broad and the answers would be opinion-based.
Third, you're still asking for a product to solve your problem (we don't do product recommendations) and even if you weren't asking for a product, it would be very hard to tell what you're actually asking.
This is why your question didn't pass the review in the reopen queue, twice. And that's likely to be the reason for the automatic deletion.