I unpacked the Bsa files so I could use the creation kit with some characters but doing this bogs the game to an almost stand still... Is there some work around for this ?

Pack them back up! That's why they are in the BSA, and with them unpacked they are overriding every single packed file, so it effectively takes the game twice as long to load everything. (If I understand all this BSA garble correctly...) Unpack JUST the files you need for your character thing. It's a bad idea to just have all the files unpacked as it can have undesired effects, such as your game slowing to a crawl.

You can also keep the unpacked files somewhere else like skyrim/moding/data/
This allows you to browse with nifscope and similar