Visual Studio 2015 update 3 Hangs while typing in long sub

Question

I have a big problem since the last studio updates which is getting really annoying.

I have a sub that contains approximately 1000 or more lines of code. When I try to type something studio will freeze for at least 20 - 30 seconds.

What I tried: comment out 900 of 1000 lines -> still freezes but only for 5 seconds

delete commented lines -> no freeze

has anyone an idea?