Memory leak when pics are resized

Setup: WP 3.3.2, BP 1.5.5, Membership 3.0.2

One of my members uploaded a JPEG in a post via the WP app on Android.

The pic shows nicely (150 x 150) in the activity stream.
Membership Admins can view the pic in the post by clicking it. The pic resizes nicely.
No other Access levels can view the pic in the post. Regardless of browser etc.
Resource usage on the server shows that memory usage explodes and hits the limit of 1GB when members on non-admin access levels tries to access the pic.

I have tried to remove all restrictions set in the Membership plugin. The problem persists.

Any help highly appreciated!