This next update looks to bug fixing and overall performance improvements for the game. As more features get added there is a need for all features to gel together. Below you can see there is a spike in FPS at a specific point while the game is running.
In diving into the code there are instances where variables are being reallocated each frame resulting in the Update method for the shipCreation_Wall script to cause a large garbage collection wait time. If you are not familiar with garbage collection I'd highly recommend looking into it with C# as it can definitely hurt your overall performance if you don't keep it in mind. Now the only issue with the built in unity performance monitor is that it can be a little misleading depending on how many versions of this script are being used but fixing this particular instance would smooth out the game regardless.
Now there are numerous ways to deal with this such as avoiding the recreation of objects. In the event new objects must be created you can alter the frequency at which they are created as well as coming up with creative ways to use objects in multiple ways.
It may be a topic worth diving more into in a much larger post but you can see based on the image below for an even larger timeframe that the number of spikes during gameplay has been drastically reduced. This gives you a much more targeted approach and this can continue to be improved for a much more solid experience.