[Rant]
The Monstrous Vermin CRs are whack!
4 7th level characters, a cleric, fighter, rogue, and wizard run into a Huge Monstrous Spider. They have full spells, hitpoints, buffs up, and the initiative.
At the end of three rounds, the cleric and rogue are poised to around 4 strength, the wizard just has Flaming Sphere and 1 Magic Missile left, and the only reason that they didn't lose is that the fighter got a really lucky crit.
Later that evening, out of spells, buffs gone, and with three of their party nearly combat ineffectuals, a Drider strikes from ambush.
In two rounds they kill him.
Both Drider and Spider have CR 7.
For comparison, the Spider has 3x the Drider's HP, much better attacks, slightly better AC, a poison so much better its not even comparable, and in return the drider gets to use bows and has some minor (and mostly non-damaging) abilities.