After installing the module and encrypting certain user fields (about 20% of user fields, so not all and not translatable) our site took a huge performance hit (CPU usage and load time). The site become basically useless when dealing with the encrypted entities with the previous server and we migrated to a bigger one. This still didn't fix the performance issue, which is the way encrypted entities are loaded.
I can't figure out what could be done to improve the performance (we have 3.1 module version with Redis and php-fpm setup) and I think we should have a open discussion what could be done.
The questions to answer, which I can't figure out when looking at the code are:
Already addressed issues:
Active
3.1
Code
Were you able to identify specific performance bottlenecks in the module code?
One thing you can do to improve performance is to turn eval off and add the entity decrypt hooks manually. See "Dynamic entity hooks" in the README.