Upgrading to WC 3.6.1 with WC Multilingual 4.6.0 causes problems in 2nd language

I have a strange site behaviour after upgrading to both WC 3.6.1 and WC Multilingual 4.6.0. The default English version of the site works as it should, but every other language product list page is slow and it shows only first 3 products. Turning on the debugging mode shows errors Fatal error: Maximum execution time of 30 seconds exceeded in /…/wp-includes/class-wp-post.php on line 266 (paths and lines are always different). Going back to 4.4.2.1 solves the issue. Going back to 4.5.0 does not solve the issue. Ready to provide all the needed access to debug.