300k DPS translates to a MQ kill time of about 25+ seconds (Ultimate xpac MQ has 6.7M health plus multiple healing methods). That’s… not very fast, especially for a pet build.
Compared to other benchmarks for pet DPS:
Skelemancer: 10s (670k minimum DPS): https://youtu.be/H6fQ04AVR4E
The Night King: 5s (1.3M minimum DPS): https://youtu.be/qGBszUBijys
Keep in mind that actual in-game DPS is always much higher than whatever the character sheet says. There are plenty of builds that only “show” DPS of 60k but can still kill the MQ in under 10-20 seconds.