Preconditions

1. Magento with MSI
2. Load performance fixtures
   bin/magento setup:perf:generate-fixtures setup/performance-toolkit/profiles/ce/small.xml
3. Enable SQL profiler

Steps to reproduce

1. Open category page (example http://localhost/category-4.html)

Magento with MSI profiler results

SQL query example:

Magento without MSI profiler results

SQL query example:

Query with explain

With MSI:

1. With conditions
   
2. Without conditions
   

Without MSI:

Additional info

1. Build on bamboo
2. Paying attention, if we transfer all products from default stock to custom stock, page load speed approximately equal to magento without MSI.
   SQL load speed on custom stock: