visa delays for H1B Scientist

Hello all:

I am a Scientist by profession. I have previously held a H1B from Johns Hopkins Medical Institute ( Non-profit) and then got employed by a biotech company. I got laid off recently. I converted to H4 on my wife’s H1B petition. Now I got a new job offer from a non profit research institute. I am planning to go to india (chennai) this november (2015) and get it stamped. I am worried about background checks/delays. Can anyone throw some light on this based on your experiences? Will they do a bckd check again even though they have done it before?

This was my previous experience:

First time H1B (Johns Hopkins, non profit scientific research): 3 weeks delay due to background check. Was asked to submit additional docs like Resume and stuff

Second time H1B ( biotech industry): Immediate, got it in 3 days

Third time H1B to H4 : delayed for 60 days

Fourth time H4 to H1B ( non profit scientific research): ???