Visiting a list of posts or pages produces many database queries, in the order of ~1000 queries per page-load. This causes the posts list to load slowly, worsening the user experience significantly, for slower database setups.
Translation Management in some cases needs to take a number of factors into account when determining the translation status of a post. Since this information is retrieved from a number of sources, The current version of WPML TM added a number of stability improvements, significantly improving the user experience of using Translation Proxy services regarding the resilience to adverse events, e.g. hard drive damage, that require restoring a site from backup.
Unfortunately an oversight disabled part of Translation Management’s internal caching mechanisms, that are in place to reduce the number of database queries, needed to render the post’s lists for translated post types. This only comes with a performance, but not a functional impact but can cause issues for slower database setups.
The number of database queries scales somewhat linearly with the number of posts displayed on a single page. Reducing the number of posts per page via the “Number of items per page:” setting found on every WordPress posts list, automatically reduces the number of database queries in proportion.
Setting it to a lower than standard value like 15 or 10 will significantly improve performance on affected setups.
The next release of WPML will come with a fix for the issue and reduce the load-time for the affected screens to what they were in WPML 3.3.