Maplestory causes computer-wide Mini Freezes/Stutters

Sounds a lot like Blackcipher is acting up again. Oh, joy!

Using 40% of my CPU. Yup. Sounds like you're right.

EDIT: Found a fix from the Nexon forums of all places.

i found a soultuion for the time being
-start task manager
-go to processes
-click show all processes
-go to black cipher
-right click
-select set affinity
-and if u have multiple cores or spus set it to one
worked for me hope this helps"