I'm on Plesk Version 17.5.3 Update #42 last updated on Feb 28.
Earlier, I had php 5.6 (os vendor) and php 7.0 installed. It was very slow. Now I installed php 7.2. But I also with php installed other components (Dovecot, Postfix, SpamAssassin. I did not have them installed before). So maybe it was a problem with my configuration.