[v1.1.9] How to fix slow loading issue in category page?

Issue: 

I'm using version 1.1.9 on M2.4.3 but it takes hundreds of seconds to page load times. Can you assist?

Solution: 

It is our module's bug when collection filter but it does not set flags so it causes the slow loading category page.

To solve this issue, please edit these files

app/code/Bss/PreOrder/Plugin/Helper/Stock.php

app/code/Bss/PreOrder/Plugin/Model/Layer/CheckOutOfStockOptions.php

app/code/Bss/PreOrder/etc/frontend/di.xml

Please apply these files on the site.

If you have any issues, please feel free to contact us.

We'd like to help.