Looking at https://www.wpintense.com/shop/wpi-performance-plugin/
1) What kind of performance boosts should I expect for a Woocommerce site with 50K products (soon 100K products).
Running on a VPS with 2 cores, 1 GB ram and standard HD (no SSD).
2) Can it work together with WP Rocket?
3) Does it also improve the performance of paginated product category pages + product category pages that are sorted by price, name etc. (instead of the default sorting).
4) Can it work together with the Woocommerce Brands plugin?
1) 50K products – host dependent – you’re probably talking your pages are taking about 4 seconds to generate the database queries now, that will reduce to 0.2 seconds. There is other stuff included in page load that this plugin does not help – e.g. serving up static files etc, if you still have problems there, better hosting will help – check out my blog article for how to migrate to digital ocean and server pilot really easily.
2) Yes – works with all caching plugins – complements them – caching creates a copy of stuff – the WPI performance plugin makes it fast to generate the stuff in the first place
3) Yes but I’m still improving this area – if you have a particular sort order or multiple sort orders you need optimised then let me know, send me examples, i’m updating the plugin weekly
4) Pass – don’t know – would be good to find out – what is this plugin?
3) The standard Woocommerce sorting options, by price, by name etc.
4) This is the plugin: https://woocommerce.com/products/brands/
VPS is Apache. It isn’t possible to get Nginx.