We use Varnish for all our clients' M2 stores and it gives big M a boost like a boot to a turtle (just an allegory, I love animals and would not harm a turtle even to introduce the great sensation of a flight). We are well under the time to the first byte of 0.5s Google wants for good ranking but I want to see if even this can be improved.
Did somebody test the difference in the Magento 2 performance improvement used with Varnish vs Litespeed? Same production store with the same server configuration?
Somebody on this forum mentioned a good experience with Litespeed but I could not find much information about using it with Magento 2 and looks like this is not something Magento recommends.
If you used/using it, can you share your thoughts and why you choose it over Varnish?
Here's the benchmark by LiteSpeed Technologies which shows that LiteSpeed Enterprise Web Server + LiteMage Cache is up to 3 times faster than nginx + Varnish and 4 times faster than Apache + Varnish:-
They explained why it is faster than Varnish and other details at this page
Did you use this service for any production store?
Yes, when I used to run Aspiration Hosting we use LiteSpeed Enterprise Web Server + LiteMage Cache across all of our clients' stores. I believe they are still using the same setup as of today.
Litespeed offers a significant advantage as it allows you to seamlessly integrate it with your current Apache http d configuration, ensuring a smooth transition. However, our focus is not on testing this capability. The claim being made is that combining Litespeed provides notably superior performance compared to using a Varnish cache setup for Magento 2. Furthermore, it is asserted that the Litespeed setup is considerably easier to configure and implement.