because of the performance tool that is generating the requests
so each request had like the same idvisitor or was each request actually different? if all requests are the same, or from same IP ad idivisitor etc then it might put all the requests in the same queue.
Because of which all the requests are hitting the same table Matomo_log_visit and causing blockings in the DB server.
This sounds like the DB might be not too fast or maybe MyISAM DB engine is used? It shouldn’t really be a problem. We’re often running it here with 16 workers and DB is still fine with that and there isn’t much blocking happening.