String template using concrete implementation instead of external library
One probable issue is performance, suppose there are 30 tokens to be replaced. And email template has a size of 50 kb. strings are immutable in C#/.Net. That means whenever you call StringTemplate.SetAttribute it creates a new string by manipulating existing and return the new string. suppose there are 30 tokens so it will create 50KB * 29 waste string. It will create more pressure on GC and GC will collect more often which will lead to poor performance. Better to use List&lt;char&gt; to do this kind of operation.