Seeing this again on the upgrade from 5.0.6 to 5.0.7. CPU usage immediately spiked for MariaDB and HHVM after the upgrade and the website became unresponsive. Approximately 10GB of binary logs were being written every five minutes.
The only thing relevant in the php log was endless entries like this:
SlowTimer [1053ms] at runtime/ext_mysql: slow query: alter table lcwp_wfConfig modify column val longblob