Working on fix today.
In the mean time, you can safely disable Prewarm Search.
The underlying issue here is that the unit database cannot be read and written to at the same time, so you're seeing a lock while the loading occurs. And because prewarm is slow, it's a long lock.
This will be fixed in the hotfix I'm pushing today as prewarm will be removed while keeping all its speed benefits, without the additional load time (woot!).
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