The Trail Renderer is great. I am using it for long trails in my game following projectiles, however I need the projectiles to go through portals - which is where the Trail Renderer predictably leaves unwanted long streaks as the trail jumps to a distant point. Essentially I want a way to briefly suspend the production of the trail and then turn it back on and resume the trail production so there is a visible gap or break in the trail. The only solution I can think of is to create a new game object with a new Trail Renderer every time a projectile goes through the portal like this. I am concerned by increasing drawcalls (platform is android/IOS) as other posts have said that Trail Renderers don’t batch. Does anyone have any other suggestions?
Good news! 
Essentially, you want to briefly suspend the production of the trail and then turn it back on and resume the trail production so there is a visible gap or break in the trail.
The only way to do this?
Create a new game object with a new Trail Renderer every time a projectile goes through the portal like this.
In a word - you want two trail renderers on the screen. So, you need two tail renderers - that’s it.
There is no problem with performance - i mean it’s only TWO trail renderers, for goodness sake.
Simply do a test, very simply duplicate your current T.R. (say, offset 5 meters) and that will give you a good test of two of the little buggers!