Create new audio tracks - spinning wheel

[sixpointmusic]

Every time I create new audio tracks, I get a spinning wheel and lose control for 1-15min.
Create new tracks - new tracks appear - freeze and spinning wheel appears - regain control after 1-15min.

*This happens only when I have lots of plugins/instruments(more than 10) in the session and try to create new "audio" tracks.
*The more plugins/instruments I have in the session, the longer the wheel spins it seems.
*I can create instrument/aux/midi tracks normally. no spinning wheel at all.
*Restarting Protools or machine don't help.
*I have 12core and 48G Ram so the machine power is not the problem I'm guessing.
*I've been trying to figure out which plugin is causing this but I still don't know yet.

Does anyone know why this happens and how to prevent from happening?

Thanks for your help!

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Mac Pro 5,1 (Mid2010) 2x2.66 Ghz - 6core Intel Xeon
Memory:48GB 1333Mhz DDR3
OSX 10.10.5
Prootols 11.3.2
MBox Pro3